JPH0810284B2 - Method and device for aligning optical axis of optical waveguide - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is used in the field of optical communication.

The present invention relates to an optical axis alignment method and device essential for connection between optical waveguides.

[Conventional technology]

FIG. 9 shows a main part of a conventional optical waveguide optical axis aligning device. In FIG. 9, 1 is a polarizer, 2 is an objective lens, 3 and 4 are first and second optical waveguides for optical axis alignment, and 5
Is an objective lens, 6 is an analyzer, and 7 is an optical power meter.

First, the laser emission is made incident on the first optical waveguide 3 by using the objective lens 2, and then the emitted light from the second optical waveguide 4 is made into a parallel beam light by the objective lens 5. The optical power is measured by the optical power meter 7. Then, the optical axis between the two optical waveguides is adjusted by performing translation of the second optical waveguide 4 with respect to the first optical waveguide 3 and fine adjustment in a direction perpendicular to the optical axis so that the output of the optical power meter is maximized. Can be matched. In addition, the polarizer 1 and the analyzer 6 are installed before and after the objective lenses 2 and 5, and the second optical waveguide 4 is arranged with respect to the optical axis so that the stroke of the light passing through the optical waveguides 3 and 4 is minimized. By rotating, the main axes holding the polarized waves in both optical waveguides can be made to coincide with each other.

[Problems to be solved by the invention]

However, in order to newly connect another optical waveguide after the optical waveguides 3 and 4, the positions of the objective lens 5, the analyzer 6, and the optical power meter 7 must be moved, so the work for each connection is complicated. There was a problem that became. Also, when the exit end of the waveguide connected to the final stage is shielded by a substance that does not transmit light, the optical power of the light propagating through this optical waveguide cannot be detected, so There was a problem that axis alignment was difficult.

The object of the present invention is to eliminate the above-mentioned problems, thereby eliminating the work of moving and adjusting the optical system (the objective lens on the exit side, etc.) for each connection of the optical waveguide, and It is an object of the present invention to provide an optical waveguide optical axis aligning method and device that can easily perform optical axis alignment even when it is difficult to monitor the optical axis.

[Means for solving problems]

The optical waveguide optical axis aligning method of the present invention is an optical waveguide optical axis aligning method for aligning the optical axes of first and second optical waveguides arranged to face each other using light emitted from a light source having a wide spectrum width. In, the light emitted from the light source is incident on the incident end of the first optical waveguide, the light emitted from the emission end is incident on the incident end of the second optical waveguide, and the light is emitted from the first optical waveguide. Of the Fresnel reflected light generated at the end or the incident end or the exit end of the second optical waveguide, the Fresnel reflected light emitted from the incident end after traveling backward in the first optical waveguide is combined with the reference light. Then, the interference component is extracted using an optical interference means, the optical power of the Fresnel reflected light is detected from the extracted interference component, and the first optical power is adjusted so that the detected optical power has a predetermined value. And the position of the second optical waveguide. And adjusting the angle.

The optical waveguide optical axis aligning device of the present invention finely adjusts the mutual position or angle of a light source that emits light with a wide spectral width and the first and second optical waveguides that are arranged facing each other and that perform optical axis alignment. In the optical waveguide optical axis aligning device including means, an incident means for making the light emitted from the light source incident on the incident end of the first optical waveguide, and the emission of the first optical waveguide by the incident from the incident means. End or the incident end or the output end of the second optical waveguide, and after traveling backward in the first optical waveguide, the Fresnel reflected light emitted from the incident end and the reference light are combined to form an interference component thereof. A light interfering means for extracting the light, a phase modulating means for phase modulating the Fresnel reflected light or the reference light in the light interfering means, and a vibration for rotating or vibrating the first or second optical waveguide at a constant cycle. Means and Signal detection means for detecting a predetermined electric signal from the optical output from the optical interference means, and the fine adjustment of the position adjustment signals of the first and second optical waveguides according to the output from the signal detection means. And a control means provided to the means for performing.

Further, in the optical waveguide optical axis aligning device of the present invention, the incident means receives a light emitted from a light source and forms a parallel beam light having a predetermined polarization mode, an objective lens, and the parallel beam light. And an optical fiber which is incident on the incident end of the first optical waveguide and constitutes one of the entrance branch and the exit branch of the optical fiber coupler.

Further, in the optical waveguide optical axis aligning device of the present invention, the optical interference means includes an optical fiber coupler which constitutes an incident means, and Fresnel reflected light which goes backward through one of the outgoing branch portions of the optical fiber coupler and the optical fiber coupler. The light incident from one of the entrance branches to the other exit branch is combined with the reference light reflected by the total reflection mirror having the moving means provided at the exit end thereof at the other entrance branch of the optical fiber coupler. The phase modulation means may include an electrostrictive oscillator in which a portion of the optical fiber coupler near the emission end of the emission branch portion of the optical fiber coupler is wound, and an oscillator for driving the electrostrictive oscillator.

Further, in the optical waveguide optical axis aligning device of the present invention, the optical interference means is the incident end or the emission end of the first optical waveguide of the Fresnel reflected light that travels backward through one emission branch portion of the optical fiber coupler which constitutes the incidence means. An objective lens having a structure in which the Fresnel reflected light at the end is used as reference light, and the combined light of this reference light and other Fresnel reflected light is extracted from the other incident branch portion of the optical fiber coupler, and the combined light is made into parallel beam light. A beam splitter for splitting the parallel beam light into two and multiplexing reflected light, and a first total reflection mirror for totally reflecting the parallel beam light split in two by the beam splitter, and a second moving means. And a phase modulation means can include an electrostrictive oscillator attached to the second total reflection mirror and an oscillator for driving the electrostrictive oscillator.

Further, in the optical waveguide optical axis aligning device of the present invention, the optical interference means is the incidence of the first optical waveguide of the Fresnel reflected light that travels backward through one of the outgoing branch portions of the first optical fiber coupler forming the incident means. The Fresnel reflected light at the end or the exit end is used as the reference light, and the combined light of this reference light and the other Fresnel reflected light is extracted from the other incident branch portion of the first optical fiber coupler, and one incident branch portion Is coupled to the other entrance branch of the first optical fiber coupler, a total reflection mirror is provided at one exit branch, and a moving means is provided at the exit end of the other exit branch through an objective lens. A total reflection mirror is provided and includes a second optical fiber coupler that outputs output light from the other incident branch portion, and the phase modulation means is one of the output branch portions of the second optical fiber coupler. Electrostrictive vibrator optical fiber cable proximate portion the outgoing end is wound, it can include a driving oscillator.

Further, in the optical waveguide optical axis aligning device of the present invention, the vibrating means is a fine movement table with a minute rotation and minute vibration device which is included in the fine adjustment means and on which the first or second optical waveguide is mounted. be able to.

Further, in the optical waveguide optical axis aligning device of the present invention, the signal detecting means includes a photodetector for converting the output light from the optical interference means into an electric signal, and a phase modulation component and A synchronization detection device that detects a vibration component can be included.

Further, in the optical waveguide optical axis aligning device of the present invention, the synchronization detecting device includes an envelope detector that detects a phase modulation component, and a first optical waveguide or a second optical waveguide based on an output signal of the envelope detector. And a lock-in amplifier that synchronously detects a vibration component that is caused by a slight vibration.

[Action]

The present invention uses Fresnel reflected light generated at the entrance and exit ends of an optical waveguide for optical axis alignment, and a light source having a wide spectrum width, and an optical interference means that constitutes a Michelson interferometer in principle,
The optical axis of the optical waveguide is aligned so that it is detected separately from the reflected light from other parts and the optimization condition of the detected signal is satisfied (usually the maximum value or the minimum value).

Therefore, in order to monitor the Fresnel reflected light generated at each end face using an interferometer, it is not necessary to install a monitor system on the output end side, and the optical axis can be aligned even when the output light from the optical waveguide cannot be monitored. .

Further, a specific frequency modulation component is given to the Fresnel reflected light by the phase modulation means and the vibration means, this is detected by the signal detection means including the synchronization detection device, and feedback is applied by the control means to align the optical waveguide optical axis. Can be done automatically, accurately and quickly.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory view showing the first embodiment of the present invention, showing the configuration of an optical waveguide optical axis aligning device. This first embodiment is a super luminescent diode (CS Wanda, et al., Applied, which emits light with a spectral width of 200 Å).
Physics Letters (CSWang et al. Appl.Phys.L)
et.) 41, p. 589, 1982].
An optical system including an objective lens 12, a polarizer 13 and an objective lens 14 that receives the light emitted from the light source 11 and forms parallel beam light that maintains a predetermined polarization mode, and one of the incident branch portions.
The light emitted from the objective lens 14 is incident on the incident end of C _{1 and} the incident light is emitted from the emission end of one of the emission branch portions C _{2 to} the incident end of the first optical waveguide 16 for optical axis alignment. Polarization-maintaining optical fiber coupler 15 [eye
Electronic Letters (I.Yokoha, etc.)
ma et al. Electron. Lett.) Volume 20, page 1004, 1984), and the other output branch C _{3 of the} optical fiber coupler 15.
An objective lens 20 provided at the exit end of the, and a total reflection mirror 21 mounted on the moving stage 22, and a photodetector 23 coupled to the entrance end of the other entrance branch C ₄ of the optical fiber coupler 15. , An amplifier 24 that amplifies the output from the photodetector 23,
Synchronous detection device 25 including an envelope detector and a lock-in amplifier for detecting the Fresnel reflected wave component from the output of the amplifier 24
A cylindrical electrostrictive oscillator 27 around which an optical fiber cable is wound in a portion close to the emission end of one emission branch portion C ₂ of the optical fiber coupler 15 and its driving oscillator 28, a control device 26, and Second optical waveguide 17 which is placed facing the optical waveguide 16 of the optical axis alignment, a fine movement table 18 on which the first optical waveguide 16 is mounted, and a microscopic table on which the second optical waveguide 17 is mounted. It includes a fine movement table 19 with a rotating and fine vibration device.

The features of the present invention are that the objective lenses 12 and 14 and the polarizer 13 are
And an incident means composed of _one entrance branch C ₁ and _one exit branch C ₂ of the optical fiber coupler 15, an optical fiber coupler 15, an objective lens 20, and a total reflection mirror 21 having a moving stage 22. Optical interference means including the electrostrictive oscillator 27
And a phase modulation means including a driving oscillator 28, and a photodetector.
23, an amplifier 24, a signal detecting means including a synchronization detecting device 25, a vibrating means including a fine movement table 19 with a minute rotation and minute vibrating device, and a control means including a control device 26. .

Next, the operation of the device of the first embodiment and the optical waveguide optical axis alignment method of the present invention will be described.

The light emitted from the light source (super luminescent diode) 11 is collected by the objective lenses 12 and 14 and the polarizer 13 and is incident on one side of the optical fiber coupler 15.
It is incident on C ₁ . Here, using the polarizer 13, only one of the two polarization-maintaining modes of the optical fiber coupler 15 is excited at the entrance end of the entrance branch C ₁ .
The optical fiber coupler 15 splits the light incident from the entrance branch C ₁ into two directions of the exit branches C ₂ and C ₃ while maintaining the polarization. The output end of the output branch C ₂ of the optical fiber coupler 15 is arranged so as to excite only one propagation mode of the first optical waveguide 16 for optical axis alignment, and the light incident on the output branch C ₂ Enters the first and second optical waveguides 16 and 17 for optical axis alignment from the fiber exit end of the exit branch C ₂ . The Fresnel reflected light generated at the exit end of the optical waveguide 16 and at the entrance end and the exit end of 17 is again at the exit branch part.
It enters the C ₂ of the fiber through the entrance bifurcation C ₄ emitted from the fiber of the incident bifurcation C _4. Further, incident from the incident bifurcation C _1, light is distributed to the outgoing branch unit C ₃ becomes a parallel beam by the objective lens 20 installed in the fiber exit end of the emission branch portion C _3, totally reflected by the total reflection mirror 21 After that, the light again enters the exit branch C ₃ , passes through the entrance branch C ₄ , and is combined therewith with the Fresnel reflected light.

The fiber of the outgoing branch C ₂ of the optical fiber coupler 15 is wound around a cylindrical electrostrictive oscillator 27, and the electrostrictive oscillator 27 is driven by a driving oscillator 28 having a resonance frequency of 20 KHz. Light propagating in the C ₂ fiber undergoes phase modulation. That is, the Fresnel reflected light passing through the exit branch C ₂ is also phase-modulated. Therefore, the Fresnel reflection light received such phase modulation, when the reference light interfere with propagating an emission branch portion C ₃ again reflected by the total reflection mirror 21 propagates the outgoing branch section C ₃ are interference intensity Amplitude of 20KH
vibrates at z. Therefore, in the first embodiment, the amplitude of this 20 KHz component is detected by a packaging line detector (not shown) built in the synchronous detection device 25. Further, in the second optical waveguide 17, minute vibrations are applied in the horizontal direction in a plane perpendicular to the optical axis in a horizontal direction at an amplitude of 0.1 μm and a cycle of 10 Hz through the fine moving table 19, and the vibration in the interference component is generated. In order to extract the component synchronized with, the output signal of the envelope detector is synchronously detected by a lock-in amplifier (not shown) built in the synchronous detector 25. The control device 26 finely moves the fine movement table 19 vertically and horizontally according to the detection signal to adjust the optical axis.

The spectral width of the light emitted from the light source (super luminescent diode) 11 is δλ = 200Å, and the center wavelength is λ = 0.8 μm. Therefore, the coherence length δl is δl = λ ² / δλ≈30 μm. That is, when the light emitted from the light source 11 is divided into two and combined again, the optical path difference between the two combined lights is 30 μm.
Interference occurs only when they match within m.

Therefore, in FIG. 1, the total reflection mirror 21 is moved to the moving stage.
The optical path length in the interferometer including the branch point of the optical fiber coupler 15 and the total reflection mirror 21 is appropriately moved by the optical fiber coupler 15, and the branch point of the optical fiber coupler 15 and the first or second optical waveguide.
The coherence length δ for the optical path length between a specific end face of 16 or 17
By matching within l, it becomes possible to interfere only the Fresnel reflected light from a specific end face and the reference light, and the optical power of this Fresnel reflected light can be detected from this interference component.

The distance between the first optical waveguide 16 and the second optical waveguide 17 depends on the emission end of the first optical waveguide 16 and the second optical waveguide 17.
It can be measured from the position of the total reflection mirror 21 when the Fresnel reflected light generated at the incident end of ∘ interferes with the reference light.

FIG. 2 shows light propagation during tilt displacement when the first and second optical waveguides 16 and 17 are tilted at an angle θ. If there is an inclination between the waveguides, the Fresnel reflected light from the incident end of the second optical waveguide 17 becomes a field pattern asymmetric with respect to the first optical waveguide 16, and the propagation mode in the first optical waveguide 16 As shown in FIG. 3, the reflected power of the coupled reflected light coupled to this optical waveguide mode is the angle θ =
It takes a maximum value at 0 and decreases as the angle increases.
Therefore, θ = 0, that is, the two optical waveguides 16 and 17 can be arranged on a straight line by rotating the optical waveguides so that the combined optical power becomes maximum.

FIG. 4 shows the case of vertical displacement in which the second optical waveguide 17 is displaced relative to the first optical waveguide 16 by d in the direction perpendicular to the optical axis. In this case, as shown in FIG. 5, the emitted light from the first optical waveguide 16 is incident on the incident end of the second optical waveguide 17 in a symmetrical field pattern (electric field distribution), Since the parts are displaced from each other, they are coupled as a propagation mode of the second optical waveguide 17, reflected by Fresnel reflection at the exit end of this optical waveguide 17, and again the first optical waveguide.
The optical power of the light coupled to 16 decreases as the displacement d increases. Therefore, the optical power of the returning light that is Fresnel-reflected at the exit end of the second optical waveguide 17 and propagates backward in the first optical waveguide 16 is detected using an interferometer, and the optical power of this returning light is maximum. The optical axes can be aligned by displacing the optical waveguide so that

As shown in FIGS. 3 and 5, it is difficult to detect the origin (θ = 0, d = 0) with high accuracy because the amount of change in the combined reflected light power with respect to rotation or displacement is small near the maximum. . Therefore, in the first embodiment, the optical waveguide 17
A minute rotation and vibration are applied to the table by the vibrating table 19.
In this case, as shown in FIGS. 3 and 4, the signals detected in synchronization with this minute rotation or minute displacement are the angular differentiation (FIG. 3) and displacement differentiation (FIG. 5 combination) of the combined reflected light power. ), And becomes zero at θ = 0 ° d = 0 (zero method). Therefore, by detecting this synchronization signal by the lock-in amplifier in the synchronization detection device 25, the optical waveguide 17 can be set at the position of θ = 0 ° d = 0 with high accuracy.

FIG. 6 shows the result of synchronous detection of interference components. With the displacement, the differential output rapidly approaches zero near the origin,
According to the first embodiment, the optical axis can be aligned with an accuracy of ± 0.2 μm. Similarly, the inclination could be suppressed within ± 1 °.

In addition, a normal optical waveguide has a TE mode that maintains polarization.
There are two modes, TM mode, and polarization dispersion (group delay time difference) occurs between the modes accordingly. When two modes are excited at the incident end of the second optical waveguide 17,
The Fresnel reflected light that propagates through 17 and is reflected back at the exit end is
The two independent light waves have a group delay time difference corresponding to twice the polarization dispersion value of the optical waveguide 17. Therefore, it is possible to appropriately move the total reflection mirror 21 and detect the optical power of the light propagating in each of the above modes, and therefore rotate the optical waveguide 17 so that one optical power becomes zero. By doing so, the main axes can be matched. In the first embodiment, the main axes could be matched with an accuracy of ± 2 °.

FIG. 7 is an explanatory view showing the second embodiment of the present invention, and shows the configuration of the optical waveguide optical axis aligning device of the present invention. The second embodiment is obtained by modifying the optical interference means and the phase modulation means in the first embodiment of FIG. 1 as follows.

That is, the light interference means refers to the Fresnel reflected light at the incident end or the output end of the first optical waveguide 16 among the Fresnel reflected light that travels backward through one of the outgoing branch portions C ₂ of the optical fiber coupler 15 that constitutes the incident means. In this configuration, the combined light of the reference light and the other Fresnel reflected light is extracted from the incident end of the other incident branch C ₄ of the optical fiber coupler 15, and the objective lens 29 converts the combined light into parallel beam light.
A beam splitter 30 that splits the parallel beam light into two and combines the reflected light, and a right-angled concave mirror 31 as a first total reflection mirror that totally reflects the parallel beam light split into two by the beam splitter 30. And moving stage
A right-angled concave mirror 32 is included as a second total reflection mirror having 35, and the phase modulation means includes an electrostrictive oscillator 33 attached to the right-angled concave mirror 32 and an oscillator 34 for driving the electrostrictive oscillator 33.

The features of the present invention are that, in FIG. 7, the same incident means, signal detection means, vibration means and control means as those shown in FIG. 1, an objective lens 29, a beam splitter 30, and a right-angled concave mirror are used.
The optical interference means includes a right-angled concave mirror 32 having a moving stage 35 and a moving stage 35, and the phase modulation means including an electrostrictive oscillator 33 and an oscillator 34 for vibration.

Next, the operation of the apparatus of the second embodiment and the method of aligning the optical axis of the optical waveguide of the present invention will be described.

The light emitted from the light source (super luminescent diode) 11 is made incident on _one entrance branch C ₁ of the optical fiber coupler 15 by the objective lenses 12 and 14 and the polarizer 13. The optical fiber coupler 15 distributes the light incident from the side of the entrance branch C ₁ into the two directions of the exit branches C ₂ and C ₃ . The exit end of the exit branch C ₂ of the optical fiber coupler 15 is arranged so as to excite the propagation mode of the first optical waveguide 16 for adjusting the optical axis, and the light incident on the exit branch C ₂ is the exit branch. The first optical waveguide 16 from the fiber output end of C ₂ ,
Next, they propagate in the order of the second optical waveguide 17.

The Fresnel reflected light generated at the exit end of the first optical waveguide 16 and the entrance / exit end of the second optical waveguide 17 again enters the fiber of the exit branch C _{2 and} exits from the fiber of the entrance branch C ₄ . In addition, the light is incident from the entrance branch C ₁ and exits C ₃
Not returned to the fiber exit bifurcation C ₃ again it is radiated into space from the fiber exit end of the distributed light emitted bifurcation C ₃ to (fiber end face is immersed in the matching oil, Fresnel reflection at the end face Light can be ignored).

The light emitted from the entrance branch C ₄ is collimated by the objective lens 29 into a parallel beam, and the beam splitter 30
Is divided into two directions. The light passing through the beam splitter 30 is reflected by the right-angled concave mirror 32, then reflected by the beam splitter 30, reflected by the beam splitter 30, and then reflected by the right-angled concave mirror 31 and again by the beam splitter 30.
The light that has returned to the optical path is multiplexed and enters the photodetector 23. The right-angled concave mirror 32 is vibrated in the beam direction at 1 KHz by an electrostrictive oscillator 33 driven by a driving oscillator 34.
The light reflected by is subject to phase modulation. Therefore, when the light that has undergone the phase modulation and the light that does not receive the phase modulation interfere with each other, the interference intensity vibrates at 1 KHz. This signal is processed by the same method as in the first embodiment described above to perform optical axis alignment.

In the present second embodiment, the Fresnel reflected light generated at the exit end of the first optical waveguide 16 is not used as the reference light for the light distributed to the exit branch C ₃ of the optical fiber coupler 15 as in the first embodiment. It is used as a reference light. Therefore, in order to match the optical path length difference between this reference light and the Fresnel reflected light generated at each entrance / exit end, in the second embodiment, a Michelson interferometer is installed as shown in FIG. One right-angled concave mirror 32
Is moved by the moving stage 35 to adjust the optical path length of both.

In the first embodiment shown in FIG. 1, the total reflection mirror 21 was moved by δ μm by the moving stage 22 in order to change the optical path length of the reference light. However, this total reflection mirror 21
However, there was a problem that the power of the reference light incident on the outgoing branching portion C ₃ of the optical fiber coupler 15 was reduced due to the shift of the optical axis, but this problem was solved in the second embodiment. Has been done.

Further, in the first embodiment, since the reference light is the light that has reciprocated through the exit branch C ₃ , the total reflection mirror 21 for causing the Fresnel reflected light and the reference light to interfere as the optical waveguides are sequentially connected. However, the moving distance of the total reflection mirror 21 is limited by the stroke of the moving stage 22. For this reason, the number of connectable optical waveguides is limited in the first embodiment. On the other hand, in the second embodiment, since the Fresnel reflected light at the exit end of the already connected frontmost optical waveguide serves as the reference light, the moving distance of the right angle concave mirror 32 in the Michelson interferometer is basically 1 Since it can be kept within the length of each waveguide times the refractive index, there is an advantage that it does not depend on the number of connected optical waveguides.

FIG. 8 is an explanatory view showing a third embodiment of the present invention, showing the configuration of the optical waveguide optical axis aligning device of the present invention. In the third embodiment, the optical interference means and the phase conversion means in the second embodiment of FIG. 7 are modified as follows.

That is, the light interference means is the Fresnel at the incident end or the emission end of the first optical waveguide 16 of the Fresnel reflected light that travels backward through the one emission branch portion C ₂ of the first optical fiber coupler 15 that constitutes the incidence means. The reflected light is used as the reference light, and the combined light of this reference light and other Fresnel reflected light is extracted from the other incident branch C ₄ of the first optical fiber coupler 15, and one incident branch C ₅ is One of the optical fiber couplers 15 is coupled to the other entrance branch C ₄ , one exit branch C ₆ is provided with a total reflection mirror 37, and the other exit branch C ₇ is equipped with an objective lens 20 at the exit end. Move through stage 22
Total reflection mirror 21 is provided with comprises a second optical fiber coupler 36 for emitting the output light from the other incident bifurcation C _8, the phase modulation means, one of the emission branch of the second optical fiber coupler 36 C _It includes a cylindrical electrostrictive oscillator 27 around which an optical fiber cable is wound in a portion near the emitting end of ₆ , and an oscillator 28 for driving the same.

The feature of the present invention is that, in FIG. 8, a total reflection mirror having an incident means, a signal detection means, a vibrating means and a control means, an objective lens 20, and a moving stage 22, which are the same as those shown in FIG.
21, an optical interference unit including a total reflection mirror 37 and a second optical fiber coupler 36, an electrostrictive oscillator 27, and a driving oscillator 28.
And a phase modulation means including the above.

Next, the operation of the device of the third embodiment and the method of aligning the optical axis of the optical waveguide of the present invention will be described.

This third embodiment is basically the same as the second embodiment shown in FIG. 7, but in the second embodiment, the Michelson interferometer comprises a bulk type beam splitter and two right angle concave mirrors. However, in the third embodiment, this is a fiber coupler.
The difference is that it is composed of 36 and total reflection mirrors 21 and 37.
That is, the branching part C ₄ of the optical fiber coupler 15 is connected to the entrance branching part C ₅ of the optical fiber coupler 36 with the main axes aligned with each other.
The Fresnel reflected light and the reference light that have passed through C ₄ pass through the entrance branch C ₅ of the optical fiber coupler 36 and then the exit branch.
It is distributed in the direction of C ₆ and C ₇ . Fiber Optic Coupler 36
The the outgoing exit end of the branch portion C ₆ are disposed in close contact total reflection mirror 37, the light propagating through the exit branch unit C ₆ total reflection mirror
The light is totally reflected at 37, propagates through the output branch C _{6 through the} fiber again, and is emitted from the fiber at the input branch C ₈ . On the other hand, the light distributed to the exit branch C ₇ through the entrance branch C ₅ becomes a parallel beam by the objective lens 20 installed at the fiber exit end of the exit branch C ₇ , and is totally reflected by the total reflection mirror 21. After that, the light again enters the exit branch C ₇ , passes through the entrance branch C ₈ , and is combined with the light that has reciprocated through the exit branch C ₆ .

The fiber of the output branch C ₆ of the optical fiber coupler 36 is wound around the cylindrical electrostrictive oscillator 27. The electrostrictive oscillator 27 is driven by an alternating current having a resonance frequency of 20 KHz by a driving oscillator 28, and the light propagating in the fiber of the emission branching section C ₆ is subjected to phase modulation. Therefore, when the light that has undergone such phase modulation interferes with the light that has reciprocated through the exit branch C ₇ and that has not undergone phase modulation, the amplitude of the interference intensity is 20 KHz.
Vibrates at. This signal is processed in the same manner as in the first embodiment to perform optical axis alignment.

Further, as in the second embodiment shown in FIG. 7, in order to cause the reference light and the Fresnel reflected light to interfere with each other, the total reflection mirror 21 of one of the exit branch portions C ₇ in the fiber type Michelson interferometer 21
Is moved in the optical axis direction by the moving stage 22.

As described above, in the third embodiment, the interferometer is made of a fiber type, and since the multiplexing and demultiplexing of light is performed stably, there is an advantage that the reliability of signal detection is further improved. .

〔The invention's effect〕

As described above, according to the present invention, the optical axis alignment of the optical waveguide can be performed more easily and more accurately than the conventional technique by the above-described configuration, and the light emitted from the optical waveguide is not monitored. It is possible to obtain an optical waveguide optical axis aligning method and device capable of aligning optical axes even when possible, and it is extremely effective and great in aligning the main axes of optical waveguides.

Further, by completely automating the embodiment of the present invention, it is possible to realize a versatile optical waveguide optical axis aligning apparatus, and the effect is great.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the first embodiment of the present invention. FIG. 2 is an explanatory diagram of light propagation during tilt displacement. FIG. 3 is an output characteristic diagram during minute rotation. FIG. 4 is an explanatory diagram of light propagation during vertical displacement. FIG. 5 is an output characteristic diagram at the time of vertical displacement. FIG. 6 is a diagram showing a differential output waveform. FIG. 7 is an explanatory view showing the second embodiment of the present invention. FIG. 8 is an explanatory view showing the third embodiment of the present invention. FIG. 9 is an explanatory view showing a conventional example. 1, 13 ... Polarizer, 2, 5, 12, 14, 20, 29 ... Objective lens, 3, 4, 16, 17 ... Optical waveguide, 6 ... Analyzer, 7
...... Optical power meter, 11 ...... Light source, 15, 36 …… Optical fiber coupler, 18, 19 …… Fine stage, 21, 37 …… Total reflection mirror, 2
2, 35 …… Movement stage, 23 …… Photodetector, 24 …… Amplifier, 25 …… Synchronous detection device, 26 …… Control device, 27,33 ……
Electrostrictive oscillator, 28, 34 ... drive oscillator, 30 ... beam splitter, 31, 32 ... right angle concave mirror.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-60-154212 (JP, A) JP-A-57-82740 (JP, A) JP-A-59-28638 (JP, A) JP-A-57- 41607 (JP, A) JP 60-208709 (JP, A) Actually developed 62-79208 (JP, U)

Claims (9)

[Claims] 1. An optical waveguide optical axis aligning method for aligning the optical axes of first and second optical waveguides arranged opposite to each other by using light emitted from a light source having a wide spectrum width. The outgoing light is incident on the incident end of the first optical waveguide (16), the outgoing light from the outgoing end is incident on the incident end of the second optical waveguide (17), and the outgoing of the first optical waveguide Of the Fresnel reflected light generated at the end or the incident end or the exit end of the second optical waveguide, the Fresnel reflected light emitted from the incident end after traveling backward in the first optical waveguide is combined with the reference light. Then, the interference component is extracted using an optical interference means, the optical power of the Fresnel reflected light is detected from the extracted interference component, and the first optical power is adjusted so that the detected optical power has a predetermined value. And the position or angle of the second optical waveguide Waveguide optical axis alignment method characterized by integer. 2. A light source for emitting light having a wide spectrum width,
In an optical waveguide optical axis aligning device comprising means for finely adjusting the mutual position or angle of the first and second optical waveguides that are arranged to face each other, the light emitted from the light source is the first Means for entering the incident end of the optical waveguide of the first optical waveguide, and the first optical waveguide generated at the emitting end of the first optical waveguide or the incident end or the emitting end of the second optical waveguide by the incident from the incident means. An optical interference unit that multiplexes the Fresnel reflected light and the reference light emitted from the incident end after traveling backward in the waveguide and extracts the interference component, and the Fresnel reflected light or the reference light in the optical interference unit. Phase modulating means for performing phase modulation, vibrating means for rotating or vibrating the first or second optical waveguide at a constant cycle, and signal detecting means for detecting a predetermined electric signal from the optical output from the optical interference means. When, An optical waveguide optical axis aligning device, comprising: a control means for providing the fine adjustment means with position adjustment signals of the first and second optical waveguides according to the output from the signal detection means. 3. An incident means receives a light emitted from a light source (11) and forms a parallel beam light having a predetermined polarization mode, and an objective lens (12, 14); The optical waveguide according to claim (2), further comprising: an optical fiber which makes parallel beam light incident on an incident end of the first optical waveguide and constitutes one of an entrance branch portion and an exit branch portion of the optical fiber coupler (15). Optical axis alignment device. 4. The optical interference means includes an optical fiber coupler (15) which constitutes an incident means, and Fresnel reflected light which goes backward through one outgoing branching portion (C ₂ ) of the optical fiber coupler and one of the optical fiber couplers. Reference light reflected by the total reflection mirror (21) having the moving means (22) provided at the exit end of the light that has entered the other exit branch (C ₃ ) from the entrance branch (C ₁ ) And is combined at the other incident branch portion (C ₄ ) of the optical fiber coupler, and the phase modulation means is such that the optical fiber cable in the portion close to the emission end of one emission branch portion of the optical fiber coupler is wound. Electrostrictive vibrator (27) and its driving oscillator (2
The optical waveguide optical axis aligning device according to claim (2), including 8). 5. The light interfering means is an entrance end or an exit end of the first optical waveguide of the Fresnel reflected light traveling backward through one exit branch (C ₂ ) of the optical fiber coupler (15) constituting the entrance means. The reference light is the Fresnel reflected light in, and the combined light of this reference light and other Fresnel reflected light is extracted from the other incident branching part (C ₄ ) of the optical fiber coupler, and the combined light is converted into a parallel beam light. Objective lens (29), a beam splitter (30) that splits the parallel beam light into two and combines the reflected light, and a first total beam that totally reflects the parallel beam light split in two by the beam splitter. A second total reflection mirror (32) having a reflection mirror (31) and a moving means (35), wherein the phase modulation means includes an electrostrictive oscillator (33) attached to the second total reflection mirror. , Its drive oscillation (34) and claims subsection (2) optical waveguide optical axis alignment apparatus further comprising a. 6. The light interference means is one output branching part (C ₂ ) of the first optical fiber coupler (15) constituting the incident means.
The Fresnel reflected light at the entrance end or the exit end of the first optical waveguide among the Fresnel reflected light that travels backward is used as the reference light, and the combined light of this reference light and other Fresnel reflected light is Other incident branch (C ₄ )
In the configuration, one entrance branch (C ₅ ) is coupled to the other entrance branch (C ₄ ) of the first optical fiber coupler, and one exit branch (C ₆ ) is a total reflection mirror. (37) is provided, and a total reflection mirror (21) having a moving means (22) via an objective lens (20) is provided at the exit end of the other exit branch (C ₇ ) and the other entrance branch is provided. The second optical fiber coupler (36) that outputs the output light from the section (C ₈ ).
The phase modulation means includes an electrostrictive oscillator (27) around which an optical fiber cable is wound in a portion close to the emission end of one emission branch of the second optical fiber coupler, and an oscillator (28) for driving the same. The optical waveguide optical axis aligning device according to claim (2), including: 7. The vibrating means is a fine movement table (19) with a minute rotation and minute vibration device, which is included in the means for finely adjusting and mounts the first or second optical waveguide. The optical waveguide optical axis aligning device according to the item (2). 8. A signal detecting means for detecting a phase modulation component and a vibration component from an output signal from the photodetector (23) for converting output light from the optical interference means into an electric signal and an output signal from the photodetector. The optical waveguide optical axis aligning device according to claim (2), including a synchronization detecting device (25). 9. A synchronization detecting device includes an envelope detector for detecting a phase modulation component, and an oscillation component obtained by minutely vibrating the first optical waveguide or the second optical waveguide from an output signal of the envelope detector. The optical waveguide optical axis aligning device according to claim (8), further comprising a lock-in amplifier for synchronous detection.