JPS5891426A - Waveguide polarization regulator - Google Patents

Abstract

PURPOSE:To obtain a polarization regulator capble of converting incident light in any polarization state into a specific polarized component on the same substrate as an optical switch without adjustment, by occluding a light wave in an optical waveguide provided on the substrate and then adjusting it electrically through electrooptic effect. CONSTITUTION:Incident light 8 from an optical fiber has both modes TE and TM when entering an optical waveguide 1 in the form of an elliptic polarized light. Because of a metallic film on an optical waveguide 2, the propagation constant of the mode TM is greatly different between the optical waveguides 1 and 2, or nearly equal in mode TE, so only the mode Te is coupled with the optical waveguide 2 while the mode TM is coupled with a branch coupling optical waveguide 5. A voltage is applied between electrodes 6 and 7 and electrode periods compensate the phase difference between TE and TM in an optical waveguide 4, so the mode TM incident from the optical waveguide 2 to the optical waveguide 4 changes into the mode TM to propagate to an optical waveguide 5, thereby emitting TE mode light from the waveguide 5 without reference to the polarization state of the incident light 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention does not change the polarization state of light waves. Concerning the polarizing device used for cooking, the light wave was placed on the board at the back, and the 2nd
Using the 聱原字 effect, progress is being made in the development of ``an a-form that can be used all at once for communication systems and optical information processing systems related to party coordinators,'' and in these systems, information sound Plans are being made to increase the amount of energy and system sue. Therefore, in order to control a wide variety of information and improve the reliability of the system, an optical switch that can rapidly switch information transmission and repair is required. At present, the original switch using the 14L mechanical transfer 1 proposed by Mineishi et al. has been put into practical use, but 11 experts have evaluated the switching speed, switching between multiple points, adaptability to single mode fiber threads, 4g shaft note, etc. I can't get the modulus h1. As a means of obtaining the original switch that makes the above-mentioned Sakae sweat (additional), there is a method of moving the original switch using a light guide installed on the board, in other words, combining the original switch of the waveform. The way to do it is rejected.4
In the case of the waveform 9 switch, Den Rokugenji Yoka, Onban Gaku Yoka, and Mineki 9♀ Yoka are used to switch the fr and kari in the Yuanjin wave path all at once. , these young fruits have different C sizes depending on the polarization diagram of the original, so the incident line of the escape light switch is TI! Switching is performed by firing 6r in either 2 mode or 1'M mode. - 10,000, Yuan) Even if the light that has passed through the eye μ is linearly polarized light incident at the input end, it generally does not become directly polarized light at the output end. Therefore, a method has been considered in which only one polarized light component is extracted using a polarizer before entering the optical switch and then inputted into the optical switch. However, when method C is used, the unnecessary polarized light component becomes a loss. Put it away. Although it is possible to consider a method of providing different poles for the TE and TM modes and performing switching independently, this method has the disadvantage that the voltage application method is complicated. In order to apply a waveguide type optical switch to an original fiber system, it is desirable to use a polarization aM1 adjuster that aligns the incident light to one effective polarization, ie, TM mode or TE mode. It is known that such a polarization A14 adjuster is constructed using a variable phase plate and a % wavelength plate, but the above configuration requires adjustment each time the polarization state of the incident light changes. In addition, since the polarization adjuster with the above-mentioned configuration is applied only to beam-shaped light waves, a lens optical system is required to insert it between the optical node 4 bar and the original switch, and the insertion loss increases. It gets bigger. Therefore, it is desirable to form the polarization adjuster 11, which is compatible with a waveguide type optical switch, on the same substrate using an optical waveguide. Further, it is desirable that film adjustment is not necessary even if the polarization state of incident light changes.

The object of the present invention is to provide a device that satisfies all of the above conditions, that is, a device that is formed on the same substrate as the original switch and that always converts incident light of any polarization state into one polarization component without side transport. l'lf The purpose of this invention is to provide a unique polarization ammeter.

The waveguide source polarization AMi device of the present invention has two optical waveguides arranged in parallel and close to each other, and a radial waveform whose refractive index is different from that of the optical waveguide is installed on one of the optical waveguides. and a branch #88 waveguide having a branch connected to the six-way waveguide of the optical coupler, further comprising: In addition, there is a structure in which a pole 7j: which has a period in the original advancing direction is installed near the meeting point. Such a structure is
They can be configured on the same substrate. Also, top 6
By applying a constant voltage to the optical coupler, the mode of light generated in the optical coupler section is converted to the original mode propagating through another optical waveguide, and the light mode converted in the branch-coupled optical waveguide is converted into the light mode. , and light that has not been mode-converted are combined and emitted, so even if a polarized light component such as (force) is incident, it can be converted into a constant polarized light component and emitted without li4 adjustment.

Hereinafter, the present invention will be described in detail with reference to the drawings.

Figure l1g1 is a plan view showing an embodiment of the polarized A4 flasher according to the present invention. FIG. 1 (see above) Ti is diffused on a lithium niobate crystal (LINbUa) substrate 10 cut perpendicularly to the Z axis to form four original waveguides 1, 2, 3° 4 and a branch-coupled optical waveguide 5. 0 original 4 waves #61 and 2 are 2~
The optical waveguides 2 are arranged close to each other by 5 μm to form a directional coupler, and the optical waveguides 2 are coated with four gold films. The optical waveguides 1 and 2 are folded into a branch-coupled optical waveguide 5 by forming elements 4v approximately 3 and 4, respectively.

Here, the width of the optical waveguides 1, 2, 3.4 is about 5 to 15 μm. However, the optical waveguides 1 and 2 have the same width.

Further, electrodes 6.7 having a period in the original transmission diagram are installed close to the optical waveguide 4. - The period A+ of the pole 6°7 is
Letting the propagation constants of the TE mode and TM mode in the optical waveguide 4 be βTE and βTM, respectively, they are set to satisfy the above expression.

2π/A1=βTM-βTE...
...(1) The value of Ax is usually about 14 to 16 μm. Next, the operation of this embodiment will be explained. In this embodiment, the incident light 8 is the source of the light emitted from the optical fiber and is coupled into the optical waveguide 1 . Since the incident light 8 is generally in the shape of a ellipse W, when it enters the optical waveguide l, it excites the TE, ``1', M1 film.The rings of the optical waveguides l and 2 are the same, but the Since there is a gold MU, the propagation constant of the TM mode is greatly different between the four optical wave paths l and 2.However, '11
Since the propagation constant of E mode is almost not affected by the 5yifQ conversion, the propagation constant of light #1 counterpaths l and 2 are almost equal. Therefore, only the 1゛E mode of the original 4tRWlfr I If dies into the optical guide [62], and the 1-film M mode passes through as it is and is coupled to the branch-coupled optical waveguide 5 via the optical waveguide 3. When a ratio of 1 is applied between 6 and 7 electric currents, ゛4 in the y direction
field component and Ll to b(electro-optic constant ra2 of Ja substrate 10
This causes coupling between the 'I'E and TM modes.

The period of the electrodes 6 and 7 is set to compensate for the phase difference between the TE and 'l'M modes in the optical waveguide 4 as shown in equation +1), so the TE mode incident on the optical waveguide 2 to 4 is converted to TM mode, emitted, branched and combined light 4
It enters NlNr5.

As described above, in this embodiment, only the TM mode is incident on the branch pipe light guide and is synthesized. In other words, no matter what polarization state the light beam 98 is in, the source of light emitted from the polarized A14 pot of this embodiment is the '1'M mode.

Figure 2 shows the polarization modulator according to the present invention. Optical waveguides 11, 12, 13, 14 and a splitting/coupling source waveguide 15 are formed. Light 4tBL path 11°12.
The positions and shapes of the optical waveguides 13 and 14 and the branch-coupling waveguide 15 are the same as the optical waveguide l and the 2°3.4 branch-coupling source waveguide 5 of the embodiment shown in FIG. 1, respectively. However, in this embodiment, the upper pot A4 of the optical waveguide 12 is installed, and the optical waveguide 1
3, a comb-shaped electrode 1j, 17 having a period A2 in the light transmission direction is installed via 5tUz[. Period A2
IF! (This is chosen to compensate for the phase difference between the TE mode and the T mode in the 4th direction.
In this embodiment 1, 'rE excited in the optical waveguide 11
The TΔ■ mode coupled to the seventh bead conductor 11 [12] enters the optical wave path 1.3 as it is and is converted into the TE mode by the voltage applied to the comb-shaped pole 16.17. At this time, in this embodiment, one field in the X direction generated by the voltage ζ applied to the comb-shaped wc plates 16 and 17 and the ``current'' rsx are utilized. As mentioned above, in the case of fufusakuri, one' of the incident light 6 is
Illg7-de is output regardless of the light condition. In addition, due to manufacturing defects or other reasons, even if the TM 7-d is tl and is incident on the branched optical waveguide 15, the T-shaped gold as shown in FIG. By installing J14E19, it is possible to capture and remove only the corrupted TM mode.

As described above, according to the present invention, even if a source with a polarization state of (a) or (a) is incident, by applying a constant voltage to the 11i pole, it is possible to always convert it into a constant polarization component. A polarization vI4 rectifier is obtained.

Further, the polarization adjuster of the present invention can be installed on the same substrate as the 4HM type original switch, and can be coupled to the original switch using an optical waveguide with low loss.

The present invention is not limited to the above-mentioned embodiments.For example, the material installed on one of the original 24e paths constituting the directional coupler may not only be metal, but also may have a refractive index different from that of the optical waveguide. It is also possible to create a '1'E mode coupling using a shed. Tg as an optical waveguide material
, a substance having an electro-optic effect that strengthens the bond between the TM and 7-does, such as 1iTaOs crystal, and a substance having an i-optical effect, such as YIG crystal, can be used. v
If the original effect is desired, it is recommended to use a zigzag electrode in which the direction of the %fi flowing across the main path is periodically reversed.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are diagrams showing an embodiment of the N-element atq dragon device according to the present invention, and in the diagram, 10.20 is LiNbO.
5 substrates, 1, 2, and 11.12 are light pollution wave paths that are close to each other and constitute the directional coupling 6; 5, 15 are branch-coupled optical waveguides; It is unipolar with .

Claims (1)

[Claims] It comprises an optical coupler made of materials having different coefficients, and a branching/coupling optical equal wave path having a molecular f branch encroached on each party waveguide of the optical coupler, and further comprising: A 4-waveform-side Motoshihime ware characterized by having a prayer hibori with a 4-shape pattern having a period in the direction in which the light travels on or near the light 24 of the branching branch.