CN103151706A - Tunable external cavity semiconductor laser based on spatial light modulator - Google Patents

Abstract

The invention provides a tunable external cavity semiconductor laser based on a spatial light modulator, relating to the field of optical fiber communication, and solves the problems that under the mechanical tuning way, the existing laser is slow in tuning speed, and poor in precision, does not adapt to the demand of the further dynamic light network, cannot keep narrow dynamic line width, and is not suitable for a dense wavelength division multiplexing system. According to the tunable external cavity semiconductor laser provided by the invention, as an electric addressable spatial light modulator is adopted, the light wave frequency is controlled by digital programming and an electric signal, thus, the period of the spatial light modulator can be tuned by only changing the control signal of the spatial light modulator; the tuning speed is speeded up; and moreover, the emitted wavelength of the laser is only needed to be positioned on a special light channel, good corresponding relationship between the spatial light modulator and the lasing frequency can be realized, the correctness is ensured, and the demands of the future dynamic light network can be adapted. As the external cavity structure is adopted, a single-mode dynamic line width reducing one quantity level can be kept compared with the existing laser, and thus, the laser provided by the invention is suitable for the dense wavelength division multiplexing system.

Description

Tunable External Cavity Semiconductor Laser Based on Spatial Light Modulator

technical field

The invention relates to a laser, in particular to a tunable external cavity semiconductor laser using a dual spatial light modulator as an optical filter and an optical path adjustment element. It belongs to the field of optical fiber communication.

Background technique

Wavelength division multiplexing technology is one of the key technologies of optical fiber communication. In the wavelength division multiplexing system, each transmission channel corresponds to a light wave of a specific wavelength. Correspondingly, these transmission channels need to be equipped with a fixed corresponding wavelength laser. DFB laser is currently widely used in optical fiber communication, and has the characteristics of good wavelength stability, simple operation and easy integration. In a DFB laser, a Bragg grating is integrated in the entire cavity of the laser, so it is a distributed feedback structure. DFB lasers output a stable single-mode laser.

In practical applications, when a laser of a transmission channel fails, another laser with the same wavelength must be used to replace it. In order to make the entire wavelength division multiplexing system run more reliably, it is necessary to back up the laser for each wavelength channel. In this way, the inventory of lasers is a large number, and this also makes the daily maintenance of the optical network face great difficulties.

Tunable semiconductor lasers can overcome the above-mentioned problems. When there is a problem with the laser of one channel, the backup laser is immediately tuned to this wavelength; when the laser of another channel fails, the wavelength of the tuning laser is adjusted to the faulty wavelength. When each laser is equally likely to fail, using tunable lasers can greatly reduce laser backup. In addition, dense wavelength division multiplexing systems put forward higher requirements for lasers. It requires that the laser can still maintain a narrow linewidth during dynamic modulation, and the external cavity laser has better spectral line characteristics than the DFB laser.

Most external cavity lasers currently used use diffraction gratings for frequency selection. In the case of stable operation, the diffraction grating external cavity semiconductor laser shows a very good performance. However, this kind of laser is tuned in a mechanical way. Therefore, the tuning speed of the laser is slow, the precision is poor, and it cannot meet the needs of future dynamic optical networks.

Contents of the invention

The present invention aims to solve the problem that existing lasers are tuned mechanically, resulting in slow tuning speed and poor precision, which cannot adapt to the needs of future dynamic optical networks, and cannot maintain a narrow dynamic line width, and is not suitable for dense wavelength division multiplexing systems. To solve this problem, a tunable external cavity semiconductor laser based on a spatial light modulator is proposed.

Tunable external cavity semiconductor laser based on spatial light modulator, which includes: high reflection coating, laser diode, anti-reflection coating, collimating lens, spatial light modulator and mirror, collimating lens, spatial light modulator and mirror are all located in the outer cavity of the laser, and the spatial light modulator is an electrically addressable spatial light modulator;

The light-emitting surface of the laser diode is coated with an anti-reflection film, and the non-light-emitting surface is coated with a high-reflection film. The light waves generated and emitted by the laser diode enter the outer cavity of the laser through the anti-reflection film, and are collimated by the collimator lens in the external cavity. Incident to the spatial light modulator, the spatial light modulator splits the light waves to obtain reflected light waves and diffracted light waves, the reflected light waves are emitted from the normal reflection direction of the spatial light modulator, and the diffracted light waves are diffracted to the On the reflector, the reflector reflects the light wave along the incident light path to the spatial light modulator, diffracts through the spatial light modulator to the collimator lens, transmits through the collimator lens, enters the laser diode through the anti-reflection film, passes through the The light transmitted by the laser diode is reflected by the high reflection film and then reflected into the laser diode.

The above-mentioned tunable external cavity semiconductor laser based on the spatial light modulator also includes: a spatial light modulator base, a PZT piezoelectric ceramic and a mirror base; the spatial light modulator is fixed on the spatial light modulator base, and the PZT The piezoelectric ceramics are fixed on the reflector base, and the reflector is fixed on the PZT piezoelectric ceramics.

Tunable external cavity semiconductor laser based on spatial light modulator, which includes: high reflection film, laser diode, anti-reflection film, collimator lens, spatial light modulator and second spatial light modulator, collimator lens, spatial light modulation Both the laser and the second spatial light modulator are located in the external cavity of the laser, and the spatial light modulator is an electrically addressable spatial light modulator;

The light-emitting surface of the laser diode is coated with an anti-reflection film, and the non-light-emitting surface is coated with a high-reflection film. The light waves generated and emitted by the laser diode enter the outer cavity of the laser through the anti-reflection film, and are collimated by the collimator lens in the external cavity. Incident to the spatial light modulator, the spatial light modulator splits the light waves to obtain reflected light waves and diffracted light waves, the reflected light waves are emitted from the normal reflection direction of the spatial light modulator, and the diffracted light waves are not perpendicular to the second spatial light modulator The direction of the surface is diffracted to the second spatial light modulator, and the second spatial light modulator reflects the light wave along the incident light path to the spatial light modulator, and is diffracted by the spatial light modulator to the collimator lens, and the collimated After the lens is transmitted, it enters the laser diode through the antireflection film, and the light transmitted through the laser diode is reflected by the high reflection film and then reflected into the laser diode.

The above-mentioned tunable external cavity semiconductor laser based on the spatial light modulator also includes: a spatial light modulator base, a PZT piezoelectric ceramic and a second spatial light modulator base; the spatial light modulator is fixed on the spatial light modulator base On the seat, the PZT piezoelectric ceramic is fixed on the base of the second spatial light modulator, and the second spatial light modulator is fixed on the PZT piezoelectric ceramic.

A tunable external cavity semiconductor laser based on a spatial light modulator, which includes: a high reflection film, a laser diode, an antireflection film, a collimator lens, a diffraction grating and a second spatial light modulator, a collimator lens, a diffraction grating and a second The spatial light modulators are all located in the external cavity of the laser, and the spatial light modulators are electrically addressable spatial light modulators;

The light-emitting surface of the laser diode is coated with an anti-reflection film, and the non-light-emitting surface is coated with a high-reflection film. The light waves generated and emitted by the laser diode enter the outer cavity of the laser through the anti-reflection film, and are collimated by the collimator lens in the external cavity. incident to the diffraction grating, the diffraction grating splits the light wave to obtain reflected light waves and diffracted light waves, the reflected light waves are emitted from the direction normally reflected by the diffraction grating, and the diffracted light waves are diffracted to the On the second spatial light modulator, the second spatial light modulator reflects the light wave along the incident optical path to the diffraction grating, diffracts through the diffraction grating to the collimator lens, transmits the collimator lens, and enters the laser diode through the antireflection film , the light transmitted through the laser diode is reflected by the high reflection film and then reflected into the laser diode.

The above-mentioned tunable external cavity semiconductor laser based on the spatial light modulator also includes: a diffraction grating base, a PZT piezoelectric ceramic and a second spatial light modulator base; the diffraction grating is fixed on the diffraction grating base, and the PZT piezoelectric The ceramic is fixed on the base of the second spatial light modulator, and the second spatial light modulator is fixed on the PZT piezoelectric ceramic.

The present invention uses an electrical addressing spatial light modulator to change the frequency of the light wave through digital programming and electric signal control, so only the control signal of the spatial light modulator can be adjusted to realize its period tuning, thus speeding up tuning speed, and the present invention does not need to continuously frequency-modulate the laser, it only needs to position the output wavelength of the laser on a specific optical channel, and there is a good correspondence between the spatial light modulator and the lasing frequency, so the tuned The accuracy can be guaranteed, so it can adapt to the needs of future dynamic optical networks. At the same time, due to the use of the external cavity structure, the tunable external cavity semiconductor laser based on the dual spatial light modulator of the present invention can maintain a single-mode dynamic linewidth that is an order of magnitude lower than that of the existing laser, and is suitable for dense wavelength division multiplexing system.

Description of drawings

Fig. 1 is a schematic diagram of the optical path principle of the tunable external cavity semiconductor laser based on the spatial light modulator according to the first embodiment;

Fig. 2 is a schematic diagram of the optical path principle of the tunable external cavity semiconductor laser based on the spatial light modulator described in the fourth embodiment;

Fig. 3 is a schematic diagram of the optical path principle of the tunable external cavity semiconductor laser based on the spatial light modulator described in the sixth embodiment.

Detailed ways

Specific Embodiment 1: This embodiment will be specifically described with reference to FIG. 1 . The tunable external cavity semiconductor laser based on the spatial light modulator described in this embodiment includes: a high reflection film 1, a laser diode 2, an antireflection film 3, a collimating lens 4, a spatial light modulator 5 and a mirror 7 , the collimating lens 4, the spatial light modulator 5 and the reflector 7 are all located in the outer cavity of the laser, and the spatial light modulator 5 is an electrically addressable spatial light modulator;

The light-emitting surface of the laser diode 2 is coated with an anti-reflection film 3, and the non-luminous surface is coated with a high-reflection film 1. The light waves generated and emitted by the laser diode 2 enter the outer cavity of the laser through the anti-reflection film 3, and are calibrated in the external cavity. After being collimated by the straight lens 4, it enters the spatial light modulator 5. The spatial light modulator 5 splits the light waves to obtain reflected light waves and diffracted light waves. The reflected light waves are emitted from the normal reflection direction of the spatial light modulator 5. The diffracted light waves are The direction perpendicular to the surface of the reflector 7 is diffracted onto the reflector 7, and the reflector 7 reflects the light wave to the spatial light modulator 5 along the incident light path, and is diffracted to the collimator lens 4 by the spatial light modulator 5, and then After being transmitted by the straight lens 4 , it enters the laser diode 2 through the antireflection film 3 , and the light transmitted through the laser diode 2 is reflected by the high reflection film 1 and then reflected into the laser diode 2 .

The non-luminous surface of the laser diode 2 is coated with a high-reflection film 1, which provides strong feedback for the light wave and reduces the gain threshold of the laser. , and the light incident from the outside to the inside of the laser diode is reflected and emitted through the anti-reflection coating 3 on the light-emitting surface of the laser diode; the laser diode 2 generates light waves and amplifies the light waves; The emitted light directly enters the external cavity without reflection in the laser diode 2, so that no internal cavity mode occurs; the collimator lens 4 expands and collimates the light wave, reduces the divergence angle of the light wave, and improves the beam quality.

The side of the high-reflection film 1 in contact with the laser diode 2 and the reflective end face of the mirror 7 together form the two end faces of the laser resonator. The optical length between the two end faces is the optical cavity length of the laser. According to the longitudinal direction of the laser According to the mode theory, the optical cavity length of the laser should be an integer multiple of half the wavelength of the laser output light, and the mirror 7 provides feedback for the light wave, and at the same time it can only make the light wave incident perpendicular to the mirror surface return along the original path.

The spatial light modulator 5 is used as an optical filter to enable the laser to perform single-mode operation; the electrically addressable spatial light modulator can accurately control the optical properties of the material in each pixel, which is beneficial to the precise control of the laser, so the present invention uses The electrical addressable spatial light modulator can manipulate the control signal of the spatial light modulator 5 through digital programming, so that the spatial light modulator 5 forms a periodic structure similar to a grating, and modulates the light waves incident on it. At this time The period length of the spatial light modulator 5 can be changed, and the rapid modulation of its period can be realized by changing the control signal of the spatial light modulator 5; when the control signal changes, the period changes, corresponding to the The frequency of the light wave on 7 also changes correspondingly, since each independent pixel unit in the spatial light modulator 5 is discrete, so its reflection peak also changes discretely, only by changing the control signal on the spatial light modulator 5 , different longitudinal mode modes can be selected to achieve coarse adjustment of the laser frequency.

Specific implementation mode two: This implementation mode further explains the tunable external cavity semiconductor laser based on the spatial light modulator described in the first mode. In this embodiment mode, it also includes: a spatial light modulator base 6, a PZT piezoelectric Ceramic 8 and reflector base 9;

The spatial light modulator 5 is fixed on the base 6 of the spatial light modulator, the PZT piezoelectric ceramic 8 is fixed on the reflector base 9 , and the reflector 7 is fixed on the PZT piezoelectric ceramic 8 .

The spatial light modulator base 6 can mechanically adjust the position and direction of the spatial light modulator 5 , and the reflector base 9 can mechanically adjust the position and direction of the reflector 7 .

PZT piezoelectric ceramic 8 can realize the fine adjustment of frequency, adjust the electrical signal of PZT piezoelectric ceramic 8, the optical cavity length of the laser will change, and the longitudinal mode of the laser will also move accordingly. Continuous tuning can be realized in the network, that is, the lasing wavelength of the laser can be precisely controlled.

The tunable external cavity semiconductor laser based on the spatial light modulator is fixed on a sealed mechanical platform, and the spatial light modulator base 6 and the mirror base 9 are respectively fixed on the mechanical platform. The sealed mechanical platform can ensure that the laser is protected from Influenced by external temperature and air flow, after taking certain anti-shock measures, the laser can resist strong external vibrations; by changing the position of the reflector 7, the cavity length of the laser resonator is changed, changing the angle of the reflector 7, from The angle of the light wave diffracted by the spatial light modulator 5 will change, so that the reflection peak will change. By changing the position and direction of the spatial light modulator 5, the cavity length and reflection peak of the laser resonator can also be changed; Therefore, the laser can not only realize the tuning of discrete wavelengths, but also realize continuous tuning within a certain range.

Specific Embodiment Three: This embodiment will be specifically described with reference to FIG. 2 . The tunable external cavity semiconductor laser based on the spatial light modulator described in this embodiment includes: a high reflection film 1, a laser diode 2, an antireflection film 3, a collimating lens 4, a spatial light modulator 5 and a second space The light modulator 10, the collimator lens 4, the spatial light modulator 5 and the second spatial light modulator 10 are all located in the external cavity of the laser, and the spatial light modulator 5 is an electrically addressable spatial light modulator;

The light-emitting surface of the laser diode 2 is coated with an anti-reflection film 3, and the non-luminous surface is coated with a high-reflection film 1. The light waves generated and emitted by the laser diode 2 enter the outer cavity of the laser through the anti-reflection film 3, and are calibrated in the external cavity. After being collimated by the straight lens 4, it enters the spatial light modulator 5. The spatial light modulator 5 splits the light waves to obtain reflected light waves and diffracted light waves. The reflected light waves are emitted from the normal reflection direction of the spatial light modulator 5. The diffracted light waves are The direction not perpendicular to the surface of the second spatial light modulator 10 is diffracted onto the second spatial light modulator 10, and the second spatial light modulator 10 reflects the light wave to the spatial light modulator 5 along the incident light path, and passes through the space The light modulator 5 diffracts to the collimator lens 4, and after being transmitted by the collimator lens 4, it enters the laser diode 2 through the antireflection film 3, and the light transmitted by the laser diode 2 is reflected by the high reflection film 1 and then reflected to the laser diode 2 middle.

When the reflection plane of the second spatial light modulator 10 is perpendicular to the diffracted light beam of the spatial light modulator 5, this embodiment and the first embodiment are equivalent technical solutions; when the reflection plane of the second spatial light modulator 10 is perpendicular to When the diffracted light beam of the spatial light modulator 5 is not vertical, the angular frequency selection function of the second spatial light modulator 10 can make the laser light emit to a new frequency; both spatial light modulators are equivalent to diffraction gratings, and the periods of the gratings are both is variable, the whole device is more flexible, and the tuning range of the laser is larger.

Specific Embodiment 4: This embodiment further describes the tunable external cavity semiconductor laser based on the spatial light modulator described in the third method. In this embodiment, it also includes: a spatial light modulator base 6, a PZT piezoelectric Ceramic 8 and second spatial light modulator base 11;

The spatial light modulator 5 is fixed on the spatial light modulator base 6 , the PZT piezoelectric ceramic 8 is fixed on the second spatial light modulator base 11 , and the second spatial light modulator 10 is fixed on the PZT piezoelectric ceramic 8 .

Embodiment 5: This embodiment will be described in detail with reference to FIG. 3 . The tunable external cavity semiconductor laser based on the spatial light modulator described in this embodiment includes: a high reflection film 1, a laser diode 2, an antireflection film 3, a collimator lens 4, a diffraction grating 12 and a second spatial light modulator The device 10, the collimating lens 4, the diffraction grating 12 and the second spatial light modulator 10 are all located in the external cavity of the laser, and the spatial light modulator 5 is an electrically addressable spatial light modulator;

The light-emitting surface of the laser diode 2 is coated with an anti-reflection film 3, and the non-luminous surface is coated with a high-reflection film 1. The light waves generated and emitted by the laser diode 2 enter the outer cavity of the laser through the anti-reflection film 3, and are calibrated in the external cavity. After being collimated by the straight lens 4, it enters the diffraction grating 12. The diffraction grating 12 splits the light wave to obtain a reflected light wave and a diffracted light wave. The direction of the surface of the spatial light modulator 10 is diffracted onto the second spatial light modulator 10, and the second spatial light modulator 10 reflects the light wave along the incident light path to the diffraction grating 12, and then diffracts the light wave to the collimating lens 4, After being transmitted by the collimator lens 4 , it enters the laser diode 2 through the antireflection film 3 , and the light transmitted through the laser diode 2 is reflected by the high reflection film 1 and then reflected into the laser diode 2 .

Specific Embodiment Six: This embodiment further describes the tunable external cavity semiconductor laser based on the spatial light modulator described in the fifth embodiment. In this embodiment, it also includes: a diffraction grating base 13, a PZT piezoelectric ceramic 8 and the second spatial light modulator base 11;

The diffraction grating 12 is fixed on the diffraction grating base 13 , the PZT piezoelectric ceramic 8 is fixed on the second spatial light modulator base 11 , and the second spatial light modulator 10 is fixed on the PZT piezoelectric ceramic 8 .

Claims (6)

1. The tunable external cavity semiconductor laser based on the spatial light modulator is characterized in that it includes: a high reflection film (1), a laser diode (2), an antireflection film (3), a collimating lens (4), a space The light modulator (5) and the mirror (7), the collimator lens (4), the spatial light modulator (5) and the mirror (7) are all located in the outer cavity of the laser, and the spatial light modulator (5) is an electrical addressable spatial light modulator; The light-emitting surface of the laser diode (2) is coated with an anti-reflection film (3), and the non-luminous surface is coated with a high-reflection film (1). The light waves generated and emitted by the laser diode (2) enter the laser through the anti-reflection film (3) The external cavity of the external cavity is collimated by the collimating lens (4) and then enters the spatial light modulator (5). The spatial light modulator (5) splits the light waves to obtain reflected light waves and diffracted light waves. The reflected light waves Emitted from the normal reflection direction of the spatial light modulator (5), the diffracted light wave is diffracted onto the reflector (7) in a direction perpendicular to the surface of the reflector (7), and the reflector (7) reflects the light wave along the incident light path to On the spatial light modulator (5), it diffracts to the collimator lens (4) through the spatial light modulator (5), and is incident to the laser diode (2) through the antireflection film (3) after being transmitted through the collimator lens (4). ), the light transmitted by the laser diode (2) is reflected by the high reflection film (1) and then reflected into the laser diode (2). 2. the tunable external cavity semiconductor laser based on spatial light modulator according to claim 1, is characterized in that, it also comprises: spatial light modulator base (6), PZT piezoelectric ceramics (8) and mirror base (9); The spatial light modulator (5) is fixed on the base of the spatial light modulator (6), the PZT piezoelectric ceramic (8) is fixed on the reflector base (9), and the reflector (7) is fixed on the PZT piezoelectric ceramic ( 8) on. 3. The tunable external cavity semiconductor laser based on the spatial light modulator is characterized in that it includes: a high reflection film (1), a laser diode (2), an antireflection film (3), a collimating lens (4), a space The light modulator (5) and the second spatial light modulator (10), the collimator lens (4), the spatial light modulator (5) and the second spatial light modulator (10) are all located in the outer cavity of the laser, and the space The light modulator (5) is an electrically addressable spatial light modulator; The light-emitting surface of the laser diode (2) is coated with an anti-reflection film (3), and the non-luminous surface is coated with a high-reflection film (1). The light waves generated and emitted by the laser diode (2) enter the laser through the anti-reflection film (3) The external cavity of the external cavity is collimated by the collimating lens (4) and then enters the spatial light modulator (5). The spatial light modulator (5) splits the light waves to obtain reflected light waves and diffracted light waves. The reflected light waves Emitted from the normal reflection direction of the spatial light modulator (5), the diffracted light wave is diffracted to the second spatial light modulator (10) in a direction not perpendicular to the surface of the second spatial light modulator (10), and the second The spatial light modulator (10) reflects the light wave to the spatial light modulator (5) along the incident light path, diffracts through the spatial light modulator (5) to the collimator lens (4), and transmits the light wave through the collimator lens (4) Afterwards, it enters the laser diode (2) through the antireflection film (3), and the light transmitted through the laser diode (2) is reflected by the high reflection film (1) and then reflected into the laser diode (2). 4. the tunable external cavity semiconductor laser based on spatial light modulator according to claim 3, is characterized in that, it also comprises: spatial light modulator base (6), PZT piezoelectric ceramics (8) and second Spatial light modulator base (11); The spatial light modulator (5) is fixed on the base of the spatial light modulator (6), the PZT piezoelectric ceramic (8) is fixed on the base of the second spatial light modulator (11), and the second spatial light modulator (10 ) is fixed on the PZT piezoelectric ceramic (8). 5. A tunable external cavity semiconductor laser based on a spatial light modulator, characterized in that it includes: a high reflection film (1), a laser diode (2), an antireflection film (3), a collimator lens (4), a diffractive The grating (12) and the second spatial light modulator (10), the collimator lens (4), the diffraction grating (12) and the second spatial light modulator (10) are all located in the outer cavity of the laser, and the spatial light modulator ( 5) A spatial light modulator for electrical addressing; The light-emitting surface of the laser diode (2) is coated with an anti-reflection film (3), and the non-luminous surface is coated with a high-reflection film (1). The light waves generated and emitted by the laser diode (2) enter the laser through the anti-reflection film (3) In the external cavity, after being collimated by the collimating lens (4), it enters the diffraction grating (12), and the diffraction grating (12) splits the light wave to obtain reflected light waves and diffracted light waves. (12) The direction of normal reflection is emitted, and the diffracted light wave is diffracted to the second spatial light modulator (10) in a direction not perpendicular to the surface of the second spatial light modulator (10), and the second spatial light modulator (10) ) reflects the light wave along the incident light path to the diffraction grating (12), diffracts through the diffraction grating (12) to the collimator lens (4), transmits through the collimator lens (4), and enters the laser through the anti-reflection film (3) A diode (2), the light transmitted by the laser diode (2) is reflected by the high reflection film (1) and then reflected into the laser diode (2). 6. the tunable external cavity semiconductor laser based on spatial light modulator according to claim 5, is characterized in that, it also comprises: Diffraction grating base (13), PZT piezoelectric ceramics (8) and second spatial light modulator base (11); The diffraction grating (12) is fixed on the diffraction grating base (13), the PZT piezoelectric ceramic (8) is fixed on the second spatial light modulator base (11), and the second spatial light modulator (10) is fixed on the PZT On the piezoelectric ceramic (8).

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