A multi-stage traveling wave semiconductor laser amplifier

Abstract

The application provides a multi-stage traveling wave semiconductor laser amplifier, comprising a semiconductor chip amplification array, a light source traveling wave unit, an amplification traveling wave unit, a pre-merging adjustment unit and a beam combiner; the semiconductor chip amplification array comprises a laser light source chip and a one-dimensional array of an even number of amplification laser chips arranged closely in a plane through the side surface; the light source traveling wave unit comprises an aspherical convex lens, a filter, a first right-angle prism and a first fast-axis lens; the amplification traveling wave unit comprises a second fast-axis lens, a second right-angle prism and a third fast-axis lens; the pre-merging adjustment unit comprises a fourth fast-axis lens, a slow-axis lens and an optical path adjustment mirror; the semiconductor chip amplification array is used for outputting amplified laser in stages, each stage of output is matched with the light source traveling wave unit or the amplification traveling wave unit to improve the quality of the light beam, and then the beam combiner is used for merging and outputting. The application has the advantages of small size, high efficiency, polarization independence and high reliability.

Description

Technical Field

[0001] This invention relates to a semiconductor laser amplifier, specifically a multi-stage traveling-wave semiconductor laser amplifier. Background Technology

[0002] like Figure 1 The diagram shows the structure of a basic gain unit in a traditional semiconductor laser amplifier. It uses four laser chips arranged separately in a planar array to form a two-dimensional array. The SLED laser chip serves as the laser pump source, and after amplification by multiple SOA laser chips, a multi-stage traveling-wave semiconductor laser amplifier is formed. Because the multiple laser chips are arranged in a two-dimensional, separate planar array, they require a large amount of space, have a limited number, and require precise placement and angle adjustments. This results in demanding manufacturing processes, leading to the problems of large size, high cost, limited gain, polarization sensitivity, and poor reliability in traditional semiconductor laser amplifiers.

[0003] Therefore, in order to obtain higher power, better wavefront quality and higher reliability, it is necessary to develop new types of semiconductor laser amplifiers. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a multi-stage traveling wave semiconductor laser amplifier, which has the advantages of small size, high efficiency, polarization independence and high reliability.

[0005] The present invention is implemented as follows: a multi-stage traveling-wave semiconductor laser amplifier, characterized in that it includes a semiconductor chip amplification array, a light source traveling-wave unit, an amplification traveling-wave unit, a pre-combining adjustment unit, and a beam combiner; The semiconductor chip amplification array includes a laser source chip and an even number of expandable amplification laser chips arranged in a close planar arrangement on the sides, forming a one-dimensional array. The even number of amplification laser chips are symmetrically distributed on both sides of the laser source chip, and both ends of the laser source chip are light-emitting surfaces. Each amplification laser chip is independently pumped and excited, and can output a separate laser beam. One end face is the light-emitting surface, and the other end face is the light-incident surface. The traveling wave unit of the light source is used to receive one light-emitting surface of the laser light source chip and one light-incident surface of the adjacent amplifying laser chip, and includes an aspherical convex lens, a filter, a first right-angle cone prism and a first fast-axis lens. The light beam from one light-emitting surface of the laser light source chip is collimated by the aspherical convex lens, the required laser wavelength is selected by the filter, and the optical path direction is adjusted twice by 90 degrees by the first right-angle cone prism to output a traveling wave. After wavefront correction and polarization control by the first fast-axis lens, it enters one light-incident surface of the adjacent amplifying laser chip. The amplifying traveling wave unit is used to receive one light-incident surface and one light-outcident surface of two adjacent amplifying laser chips, and includes a second fast-axis lens, a second right-angle cone prism and a third fast-axis lens. The light beam from one light-outcident surface of the amplifying laser chip is corrected for wavefront and polarization by the second fast-axis lens, and then the light path direction is adjusted twice by 90 degrees by the second right-angle cone prism to output a traveling wave. The third fast-axis lens then corrects for wavefront and polarization again before entering one light-incident surface of the adjacent amplifying laser chip. The pre-merging adjustment unit is located between the light-emitting surfaces of the two outermost amplifying laser chips in the semiconductor chip amplification array and the beam combiner, and includes a fourth fast-axis lens, a slow-axis lens, and an optical path adjustment mirror. The light emitted from the light-emitting surfaces of the two outermost amplifying laser chips in the semiconductor chip amplification array undergoes beam wavefront correction and polarization control by the fourth fast-axis lens, its direction is adjusted by the optical path adjustment mirror, and then controlled by the slow-axis lens to compensate for the slow-axis distortion, thereby correcting the slow-axis wavefront of the beam, before entering the beam combiner for merging.

[0006] Furthermore, it also includes a miniature photodetector located at the rear end of the beam combiner, which detects the parameters of each beam received from the beam combiner in real time and provides real-time feedback.

[0007] Furthermore, it also includes a bandpass filter to select the wavelength of the light emitted from the miniature photodetector before outputting it.

[0008] Furthermore, the optical path adjustment mirror is a reflector or a right-angle conical prism; the beam combiner is a polarizing beam splitter.

[0009] Furthermore, in the semiconductor chip amplification array, one or more of the amplified laser chips are allowed to be disconnected from the optical path on both sides of the laser source chip, forming a backup structure for each other.

[0010] Furthermore, it also includes a single thermoelectric cooler disposed below the semiconductor chip amplification array for temperature control.

[0011] The advantages of this invention are as follows: The multi-stage traveling-wave semiconductor laser amplifier of this invention has a semiconductor chip amplification array consisting of a laser source chip and an even number of expandable amplification laser chips arranged in a tightly planar configuration on the side, forming a one-dimensional array structure. Different chips are coherently coupled and jointly output as the basic gain unit. The expandable amplification laser chips form multiple series amplification stages, thereby obtaining higher amplification gain. The tightly planar arrangement of the one-dimensional array structure can form a compact structure, greatly reducing the volume of the semiconductor laser amplifier. Moreover, this one-dimensional array structure is easy to operate in terms of arrangement, which greatly reduces the manufacturing cost. After each amplification stage, wavefront correction and polarization control are performed through the light source traveling-wave unit or the amplification traveling-wave unit, thereby obtaining good wavefront quality and polarization-independent output. Furthermore, the compact traveling-wave guide structure is beneficial for thermal management. A monitoring feedback mechanism is also introduced to dynamically optimize the amplification process, which has the advantages of high reliability, high efficiency, and the ability to form a mutual backup protection structure. Attached Figure Description

[0012] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0013] Figure 1 This is a schematic diagram of a traditional multi-stage traveling-wave semiconductor laser amplifier.

[0014] Figure 2 This is a schematic diagram of the multi-stage traveling-wave semiconductor laser amplifier of the present invention. Detailed Implementation

[0015] This invention provides a multi-stage traveling-wave semiconductor laser amplifier, which has the advantages of small size, high efficiency, polarization independence, and high reliability.

[0016] The technical solution in this invention aims to solve the above-mentioned problems. The overall concept is as follows: The multi-stage traveling-wave semiconductor laser amplifier of this invention has a semiconductor chip amplification array composed of a laser source chip and an even number of expandable amplification laser chips arranged in a tight planar configuration on the side, forming a one-dimensional array structure. Different chips are coherently coupled and jointly output as the basic gain unit. The expandable amplification laser chips form multiple series amplification stages, thereby obtaining higher amplification gain. The one-dimensional array structure arranged in a tight planar configuration can form a compact structure, greatly reducing the volume of the semiconductor laser amplifier. Moreover, this one-dimensional array structure is easy to operate in terms of arrangement, which greatly reduces the manufacturing cost. After each amplification stage, wavefront correction and polarization control are performed through the light source traveling-wave unit or the amplification traveling-wave unit, thereby obtaining good wavefront quality and polarization-independent output. Furthermore, the compact traveling-wave guide structure is beneficial for thermal management. A monitoring feedback mechanism is also introduced to dynamically optimize the amplification process, which has the advantages of high reliability, high efficiency, and mutual backup protection.

[0017] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0018] Please see Figure 2 As shown, a multi-stage traveling-wave semiconductor laser amplifier 100 according to an embodiment of the present invention includes a semiconductor chip amplification array 1, a light source traveling-wave unit 2, an amplification traveling-wave unit 3, a pre-combining adjustment unit 4, and a beam combiner 5. The semiconductor chip amplification array 1 includes a laser source chip 11 and an even number of expandable amplification laser chips 12 arranged in a close planar arrangement on the sides, forming a one-dimensional array. The even number of amplification laser chips 12 are symmetrically distributed on both sides of the laser source chip 11, and both ends of the laser source chip 11 are light-emitting surfaces. Each amplification laser chip 12 is independently pumped and excited, and can output a separate laser beam. One end face is the light-emitting surface, and the other end face is the light-incident surface. The semiconductor chip amplification array 1 serves as the basic gain unit of the multi-stage traveling wave semiconductor laser amplifier 100, with different semiconductor chips coherently coupled and jointly outputting.

[0019] The traveling wave unit 2 is used to receive one light-emitting surface of the laser light source chip 11 and one light-incident surface of the adjacent amplifying laser chip 12. It includes an aspherical convex lens 21, a filter 22, a first right-angle cone prism 23 and a first fast-axis lens 24. The light beam from one light-emitting surface of the laser light source chip 11 is collimated by the aspherical convex lens 21, the filter 22 selects the required laser wavelength, and then the first right-angle cone prism 23 adjusts the optical path direction twice by 90 degrees to output a traveling wave. The light beam is then corrected by the first fast-axis lens 24 and polarization is controlled before entering one light-incident surface of the adjacent amplifying laser chip 12. The amplifying traveling wave unit 3 is used to receive one light-incident surface and one light-outcident surface of two adjacent amplifying laser chips 12, and includes a second fast-axis lens 31, a second right-angle cone prism 32 and a third fast-axis lens 33. The light beam from one light-outcident surface of the amplifying laser chip 12 is corrected for wavefront and polarization by the second fast-axis lens 31, and then the light path direction is adjusted twice by 90 degrees by the second right-angle cone prism 32 to be output as a traveling wave. The third fast-axis lens 33 corrects for wavefront and polarization again before entering one light-incident surface of the adjacent amplifying laser chip 12. The pre-merging adjustment unit 4 is located between the light-emitting surfaces of the two outermost amplifying laser chips 12 in the semiconductor chip amplification array 1 and the beam combiner 5, and includes a fourth fast-axis lens 41, an optical path adjustment mirror 42, and a slow-axis lens 43. The light emitted from the light-emitting surfaces of the two outermost amplifying laser chips 12 in the semiconductor chip amplification array 1 undergoes beam wavefront correction and polarization control by the fourth fast-axis lens 41, its direction is adjusted by the optical path adjustment mirror 42, and then controlled by the slow-axis lens 43 to compensate for the slow-axis distortion and correct the slow-axis wavefront of the beam before entering the beam combiner 5 for merging. The optical path adjustment mirror 42 can be a reflector or a right-angle cone prism, depending on the angle of the light beam to be modified.

[0020] The beam combiner 5 is a polarized beam splitter (PBS) used to combine multiple laser beams. The PBS splits light into two mutually perpendicular polarized beams based on the direction of light polarization. When two mutually perpendicular laser beams are incident on the PBS, the beams are combined. Typically, a waveplate is needed to adjust the two beams to a mutually perpendicular polarization state. PBS beam combining can combine light of different wavelengths without the need for filters. It has high combining efficiency, low loss, and the polarization state of the combined beam is consistent with that of the incident light. It has a simple and compact structure, making it easy to align the optical path. It is a simple and efficient method for laser beam combining and has wide applications, such as optical communication, laser display, and optical storage.

[0021] Furthermore, this embodiment also includes a miniature photodetector 6 (mPD); located at the rear end of the beam combiner 5, it detects and provides real-time feedback on the parameters of each beam received from the beam combiner 5. The parameters of each beam include beam position, beam size, polarization state, light intensity fluctuation, and beam quality results. By monitoring the beam position, it ensures the beam is correctly incident on the PBS; by monitoring the beam size, it ensures the beam meets the PBS's incident requirements; by detecting the beam polarization state, it ensures matching with the PBS design; by monitoring light intensity fluctuations, it provides feedback to adjust the laser output; and by detecting beam quality parameters such as wavefront distortion, it feeds the monitoring results back to the beam control system in real time to automatically optimize the beam parameters, ensuring the efficiency and quality of beam combining, avoiding losses caused by beam deviation or polarization state, making the PBS beam combining system stable and reliable, and improving beam combining accuracy.

[0022] Furthermore, this embodiment also includes a bandpass filter 7, which selects the wavelength range of the light emitted from the miniature photodetector before outputting it. The bandpass filter 7 only allows light within a specific wavelength range to pass through, filtering out other wavelengths. By selecting the center wavelength and bandwidth of the filter according to the design, spontaneous emission and reflected light from the laser system can be filtered out, a specific wavelength of laser beam can be extracted or transmitted separately, the spectrum can be cleaned, unwanted wavelength components can be removed, and the signal-to-noise ratio of the optical system can be improved. It is commonly used in wavelength selection, spectral control, and optical communication systems. The narrower the bandpass bandwidth, the better the filtering effect, but the greater the loss. By stacking multiple filters, a more precise filtering effect can be obtained.

[0023] Furthermore, in the semiconductor chip amplification array, one or more of the amplified laser chips are allowed to be disconnected from the optical path on both sides of the laser source chip, forming a backup structure. Even when some amplified laser chips are not connected to the optical path, the entire laser will still emit light; this backup structure can handle unexpected situations and provide protection.

[0024] Furthermore, the multi-stage traveling-wave semiconductor laser amplifier of the present invention also includes a single thermoelectric cooler (TEC), which is disposed below the semiconductor chip amplification array and used for temperature control to achieve thermal management. Temperature control via a single TEC reduces the introduction of more unknown variables into the system, making it easier to control the system and creating a stable operating environment.

[0025] In this embodiment, the optical transmission process is as follows: 1) After the light source passes through the laser light source chip 11 (SLED), it will be pumped and excited to output laser light; 2) Entering the traveling wave unit 2 of the light source: First, the laser is collimated by the aspherical convex lens 21, and collimated light is output; the isolation effect of the filter 22 prevents the light from returning through the first right-angle cone prism 23 (also called the back reflector); the light passes through the first right-angle cone prism 23, and regardless of the incident angle, it can obtain a reflected ray that is always parallel to the incident ray; the reflected ray passes through the first fast-axis lens 24 and outputs the collimated laser. 3) The output of the first fast-axis lens 24 enters the first amplified laser chip 12 (SOA) for re-pumping and excitation, and outputs a laser amplified by one stage; 4) After entering the first amplified traveling wave unit 3, the laser after the first stage of amplification is corrected for wavefront and polarization by the second fast axis lens 31, and then the optical path direction is adjusted twice by 90 degrees by the second right-angle conical prism 32 to output as a traveling wave. The laser is then corrected for wavefront and polarization by the third fast axis lens 33 again, and then enters the second amplified laser chip 12 (SOA) for pumping and excitation again, and outputs the laser after the second stage of amplification. 5) Then it enters the second amplified traveling wave unit 3, and then enters the third amplified laser chip 12 (SOA) for pumping and excitation again, and outputs the laser after three stages of amplification; and so on, until it is output from the outermost amplified laser chip 12 (SOA) to obtain the laser after the last stage of amplification; 6) The laser beam after the final stage of amplification enters the pre-merging adjustment unit 4, where the beam wavefront is corrected and polarization is controlled by the fourth fast axis lens 41, the propagation direction is adjusted by the optical path adjustment mirror 42, and then the slow axis lens 43 provides dispersion opposite to the slow axis distortion to compensate for the slow axis distortion and thus correct the slow axis wavefront of the beam and improve the laser quality; then it enters the beam combiner 5 (PBS). 7) The beam combiner 5 combines the two beams, and then the beams are detected in real time by the micro photodetector 6, which detects the parameters of each beam received from the beam combiner 5 and provides real-time feedback. The final output beam is then output after bandpass filtering by the bandpass filter 7. The bandpass filter 7 also acts as an isolation filter to prevent laser backlash.

[0026] In summary, the multi-stage traveling-wave semiconductor laser amplifier of the present invention comprises a one-dimensional array structure consisting of a laser source chip and an even number of expandable amplifying laser chips arranged in a tightly planar configuration along the sides. The coherent coupling and joint output of different chips serves as the basic gain unit. The expandable amplifying laser chips form multiple cascaded amplification stages, thereby achieving higher amplification gain. The tightly planar arrangement of the one-dimensional array structure creates a compact structure, significantly reducing the size of the semiconductor laser amplifier. Furthermore, this one-dimensional array structure is easy to arrange, greatly reducing manufacturing costs. After each amplification stage, wavefront correction and polarization control are performed through the light source traveling-wave unit or the amplifying traveling-wave unit, resulting in good wavefront quality and polarization-independent output. The compact traveling-waveguide structure facilitates thermal management, and a monitoring feedback mechanism is introduced to dynamically optimize the amplification process. This results in high reliability, high efficiency, and mutual backup protection.

[0027] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A multi-stage traveling-wave semiconductor laser amplifier, characterized in that: Includes semiconductor chip amplification array, light source traveling wave unit, amplification traveling wave unit, pre-combining adjustment unit, and beam combiner; The semiconductor chip amplification array includes a laser source chip and an even number of expandable amplification laser chips arranged in a close planar arrangement on the sides, forming a one-dimensional array. The even number of amplification laser chips are symmetrically distributed on both sides of the laser source chip, and both ends of the laser source chip are light-emitting surfaces. Each amplification laser chip is independently pumped and excited, and can output a separate laser beam. One end face is the light-emitting surface, and the other end face is the light-incident surface. The traveling wave unit of the light source is used to receive one light-emitting surface of the laser light source chip and one light-incident surface of the adjacent amplifying laser chip, and includes an aspherical convex lens, a filter, a first right-angle cone prism and a first fast-axis lens. The light beam from one light-emitting surface of the laser light source chip is collimated by the aspherical convex lens, the required laser wavelength is selected by the filter, and the optical path direction is adjusted twice by 90 degrees by the first right-angle cone prism to output a traveling wave. After wavefront correction and polarization control by the first fast-axis lens, it enters one light-incident surface of the adjacent amplifying laser chip. The amplifying traveling wave unit is used to receive one light-incident surface and one light-outcident surface of two adjacent amplifying laser chips, and includes a second fast-axis lens, a second right-angle cone prism and a third fast-axis lens. The light beam from one light-outcident surface of the amplifying laser chip is corrected for wavefront and polarization by the second fast-axis lens, and then the light path direction is adjusted twice by 90 degrees by the second right-angle cone prism to output a traveling wave. The third fast-axis lens then corrects for wavefront and polarization again before entering one light-incident surface of the adjacent amplifying laser chip. The pre-merging adjustment unit is located between the light-emitting surfaces of the two outermost amplifying laser chips in the semiconductor chip amplification array and the beam combiner, and includes a fourth fast-axis lens, a slow-axis lens, and an optical path adjustment mirror. The light emitted from the light-emitting surfaces of the two outermost amplifying laser chips in the semiconductor chip amplification array undergoes beam wavefront correction and polarization control by the fourth fast-axis lens, its direction is adjusted by the optical path adjustment mirror, and then controlled by the slow-axis lens to compensate for slow-axis distortion and correct the slow-axis wavefront of the beam before entering the beam combiner for merging.

2. The multi-stage traveling-wave semiconductor laser amplifier as described in claim 1, characterized in that: It also includes a miniature photodetector located at the rear end of the beam combiner, which detects the parameters of each beam received from the beam combiner in real time and provides real-time feedback.

3. The multi-stage traveling-wave semiconductor laser amplifier as described in claim 2, characterized in that: It also includes a bandpass filter to select the wavelength of the light emitted from the miniature photodetector before outputting it.

4. The multi-stage traveling-wave semiconductor laser amplifier as described in claim 1, characterized in that: The optical path adjustment mirror is a reflecting mirror or a right-angle conical prism; The beam combiner is a polarized beam splitter.

5. A multi-stage traveling-wave semiconductor laser amplifier as described in claim 1, characterized in that: In the semiconductor chip amplification array, one or more of the amplified laser chips are allowed to be disconnected from the optical path on both sides of the laser source chip, forming a backup structure for each other.

6. The multi-stage traveling-wave semiconductor laser amplifier as described in claim 1, characterized in that: It also includes a single thermoelectric cooler disposed below the semiconductor chip amplification array.

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