An external cavity narrow linewidth laser component

Abstract

The present application relates to an external cavity narrow linewidth laser assembly, comprising: a substrate, to which a gain chip for emitting laser light is fixedly connected; a first light-transmitting reflector and a second light-transmitting reflector, spaced in sequence and located in the direction of the laser emitting end of the gain chip, are also connected to the substrate; the first light-transmitting reflector is spaced apart from the gain chip and together form a first external optical resonant cavity; the second light-transmitting reflector is spaced apart from the first light-transmitting reflector and together with the gain chip form a second external optical resonant cavity. The first and second external optical resonant cavities of the external cavity narrow linewidth laser assembly of the present application significantly increase the resonant cavity length within the limited tube shell space. The longer the resonant cavity length, the longer the coherent light length, and thus the narrower the linewidth, achieving higher performance while maintaining a low cost.

Description

Technical Field

[0001] The present application relates to the field of optical communication technology, and in particular to an external cavity narrow linewidth laser assembly. Background Art

[0002] Semiconductor lasers have many unique advantages, such as small size, high photoelectric conversion efficiency, low drive power consumption, and wide coverage. However, they also have some serious shortcomings, such as wide linewidth. Although some semiconductor lasers can reach around 10MHz, this is far from the ideal single-mode narrow linewidth (sub-kHz) required by many systems.

[0003] External cavity semiconductor lasers overcome the shortcomings of conventional semiconductor lasers, such as wide linewidth and poor frequency stability. They offer high efficiency, long life, and stable frequency, making them widely applicable in fields such as optical wave device measurement, metrology testing, water quality testing, and high-resolution spectral analysis.

[0004] In related technologies, external cavity narrow linewidth lasers generally use Gain Chip chips as laser sources. External cavity designs are generally divided into two types: the first is an integrated external chip external cavity narrow linewidth laser, and the second is a narrow linewidth laser that uses optical components to form an external cavity.

[0005] However, the first type is more expensive due to the existence of the chip, but it has excellent performance and the intrinsic linewidth can reach the Hz level; the second type is much cheaper, but has some shortcomings in performance, and can generally make the intrinsic linewidth reach the KHz level. Summary of the Invention

[0006] The embodiment of the present application provides an external cavity narrow linewidth laser assembly to solve the problem in the related art that external cavity semiconductor lasers with narrow intrinsic linewidth are expensive, while inexpensive external cavity semiconductor lasers have an intrinsic linewidth that is too narrow.

[0007] The present invention provides an external cavity narrow linewidth laser assembly, comprising:

[0008] A substrate, to which a gain chip for emitting laser light is fixedly connected, and a first light-transmitting reflector and a second light-transmitting reflector are connected to the substrate and are spaced apart from each other in the direction of the laser emitting end of the gain chip;

[0009] The first light-transmitting reflector is spaced apart from the gain chip and together they form a first external optical resonant cavity. The second light-transmitting reflector is spaced apart from the second light-transmitting reflector and together they form a second external optical resonant cavity with the gain chip.

[0010] In some embodiments, the first light-transmitting reflector and the second light-transmitting reflector are both coated with a reflective film on one side close to the laser emitting end of the gain chip, and are both coated with an anti-reflection film on one side away from the laser emitting end of the gain chip.

[0011] In some embodiments, the reflectivity of the first light-transmitting reflective mirror is greater than the reflectivity of the second light-transmitting reflective mirror, and the first light-transmitting reflective mirror and the second light-transmitting reflective mirror are both perpendicular to the laser emitting end of the gain chip.

[0012] In some embodiments, a collimating lens fixed on a substrate is provided between the laser emitting end of the gain chip and the first light-transmitting reflector, and the collimating lens is used to collimate the outgoing light of the laser emitting end of the gain chip into parallel light;

[0013] An etalon fixed on a substrate is provided between the collimating lens and the first light-transmitting reflector, and the etalon is used to convert the parallel light coupled by the collimating lens into multi-peak wide-spectrum parallel light with consistent free spectral range intervals.

[0014] In some embodiments, a filter fixed on the substrate is provided between the first light-transmitting reflector and the second light-transmitting reflector, and the passband range of the filter is consistent with the tuning range of the second external optical resonant cavity to suppress laser modes outside its passband range.

[0015] In some embodiments: an isolator and a focusing lens fixed on a substrate are provided on the side of the second light-transmitting reflector facing away from the first light-transmitting reflector, the isolator is used to block the return light of the focusing lens from returning to the second external optical resonant cavity, and the focusing lens is used to focus the collimated parallel light emitted by the gain chip into the collimating optical fiber.

[0016] In some embodiments: the collimating optical fiber is connected to a spectrometer, the substrate is provided with a slideway slidably connecting the first light-transmitting reflector and the second light-transmitting reflector, and the slideway extends along the direction of the laser emitting end of the gain chip;

[0017] The first light-transmitting reflector and the second light-transmitting reflector slide on the slideway respectively to adjust the cavity lengths of the first external optical resonant cavity and the second external optical resonant cavity, and the spectrometer displays spectral characteristics of different cavity lengths.

[0018] In some embodiments: the slide is also slidably connected to a height adjuster connected to the first light-transmitting reflector and the second light-transmitting reflector respectively, and the height adjuster is used to alternately adjust the height of the first light-transmitting reflector and the second light-transmitting reflector to match the laser modes of the first external optical resonant cavity and the second external optical resonant cavity alternately formed by the first light-transmitting reflector and the second light-transmitting reflector.

[0019] In some embodiments, a heat sink connected to the gain chip is provided on the substrate, the gain chip is attached to the heat sink by eutectic welding, the positive electrode on the surface of the gain chip is connected to one side of the heat sink by gold wire bonding, and the negative electrode on the back side of the gain chip is connected to the other side of the heat sink by adhesive bonding.

[0020] In some embodiments, the gain chip is a DFB laser, and a housing encapsulating the gain chip, the first light-transmitting reflector, and the second light-transmitting reflector is provided on the substrate.

[0021] The beneficial effects of the technical solution provided by this application include:

[0022] An embodiment of the present application provides an external cavity narrow linewidth laser assembly. The external cavity narrow linewidth laser assembly of the present application is provided with a substrate, to which a gain chip for emitting laser light is fixedly connected. The substrate is also connected to a first light-transmitting reflector and a second light-transmitting reflector that are spaced apart in sequence in the direction of the laser emitting end of the gain chip. The first light-transmitting reflector is spaced apart from the gain chip and together form a first external optical resonant cavity. The second light-transmitting reflector is spaced apart from the first light-transmitting reflector and together with the gain chip form a second external optical resonant cavity.

[0023] Therefore, the external-cavity narrow-linewidth laser assembly of the present application includes a first light-transmitting reflector and a second light-transmitting reflector spaced apart in sequence toward the laser-emitting end of the gain chip. The first light-transmitting reflector and the gain chip are spaced apart and together form a first external optical resonant cavity. The second light-transmitting reflector and the first light-transmitting reflector are spaced apart and together with the gain chip form a second external optical resonant cavity. The first and second external optical resonant cavities significantly increase the resonant cavity length within the limited tube shell space. The longer the resonant cavity length, the longer the coherent light length, and thus the narrower the linewidth, achieving higher performance while maintaining low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0025] Figure 1 This is a structural front view of an embodiment of the present application;

[0026] Figure 2 A structural perspective diagram of an embodiment of the present application;

[0027] Figure 3This is a test spectrum diagram of an embodiment of the present application.

[0028] Reference numerals:

[0029] 1. Substrate; 2. Gain chip; 3. First light-transmitting reflector; 4. Second light-transmitting reflector; 5. First external optical resonant cavity; 6. Second external optical resonant cavity; 7. Collimating lens; 8. Etalon; 9. Filter; 10. Isolator; 11. Focusing lens; 12. Heat sink. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0031] The embodiments of the present application provide an external cavity narrow linewidth laser assembly, which can solve the problem in the related art that external cavity semiconductor lasers with narrow intrinsic linewidth are expensive, while external cavity semiconductor lasers with low cost have intrinsic linewidths that are too wide.

[0032] See also Figure 1 and Figure 2 As shown, an embodiment of the present application provides an external cavity narrow linewidth laser assembly, comprising:

[0033] A substrate 1 is fixedly connected to a gain chip 2 for emitting laser light. Also connected to the substrate are a first light-transmitting reflector 3 and a second light-transmitting reflector 4, spaced apart from each other in the direction of the laser emitting end of the gain chip 2. The first light-transmitting reflector 3 is spaced apart from the gain chip 2 and together they form a first external optical resonant cavity 5. The second light-transmitting reflector 4 is spaced apart from the first light-transmitting reflector 3 and together with the gain chip 2 they form a second external optical resonant cavity 6.

[0034] The external cavity narrow linewidth laser assembly of the embodiment of the present application includes a first light-transmitting reflector 3 and a second light-transmitting reflector 4 arranged in sequence in the direction of the laser emission end of the gain chip 2, and the first light-transmitting reflector 3 is arranged at an interval from the gain chip 2 and together form a first external optical resonant cavity 5, and the second light-transmitting reflector 4 is arranged at an interval from the first light-transmitting reflector 3 and together with the gain chip 2 form a second external optical resonant cavity.

[0035] The first light-transmitting reflector 3 and the laser emitting end of the gain chip 2 form a first external optical resonant cavity 5 that resonates and amplifies only the target wavelength. The first external optical resonant cavity 5 selects the laser wavelength and continuously oscillates and amplifies it. The second light-transmitting reflector 4, the first light-transmitting reflector 3, and the laser emitting end of the gain chip 2 form a second external optical resonant cavity 6 that resonates and amplifies only the target wavelength. The second external optical resonant cavity 6 selects the laser wavelength and continuously oscillates and amplifies it.

[0036] Broadband light emitted by gain chip 2 exits the laser emitting end and is perpendicularly incident on first light-transmitting reflector 3. This first light-transmitting reflector 3 reflects the target wavelength and transmits non-target light. The reflected target wavelength enters gain chip 2, undergoes stimulated emission, and then reflects again. The gain chip 2 and first light-transmitting reflector 3 form a first external optical resonant cavity 5. Combined with the gain chip 2, this cavity repeatedly resonates and amplifies the target light, generating the first lasing emission, which is then output through first light-transmitting reflector 3.

[0037] The lasing light output from the first light-transmitting reflector 3 is perpendicularly incident on the second light-transmitting reflector 4. The second light-transmitting reflector 4 reflects the target wavelength again and transmits non-target light. The reflected target wavelength light passes through the first light-transmitting reflector 3 and enters the gain chip 2, where it is stimulated to emit radiation and then reflected again. The gain chip 2 and the second light-transmitting reflector 4 form a second external optical resonant cavity 6. In combination with the gain chip 2, the target light is repeatedly resonantly amplified, resulting in a second lasing. The lasing light is then output through the first light-transmitting reflector 3 and the second light-transmitting reflector 4.

[0038] The first external optical resonant cavity 5 and the second external optical resonant cavity 6 significantly increase the resonant cavity length within the limited tube shell space. The longer the resonant cavity length, the longer the coherent light length, and thus the narrower the line width, thereby reducing the bandwidth of the resonance while maintaining a low cost and realizing narrowband filtering. The advantages include good wavelength stability, high side mode suppression ratio, narrow line width, large adjustment tolerance, and simple manufacturing process.

[0039] In some alternative embodiments: See Figure 1 and Figure 2 As shown, an embodiment of the present application provides an external cavity narrow linewidth laser assembly, in which the first light-transmitting reflector 3 and the second light-transmitting reflector 4 of the external cavity narrow linewidth laser assembly are both coated with a reflective film on one side close to the laser emitting end of the gain chip 2, and the first light-transmitting reflector 3 and the second light-transmitting reflector 4 are both coated with an anti-reflection film on one side away from the laser emitting end of the gain chip 2.

[0040] The reflectivity of the first light-transmitting reflector 3 is greater than that of the second light-transmitting reflector 4. The first light-transmitting reflector 3 and the second light-transmitting reflector 4 are both perpendicular to the laser emitting end of the gain chip. The reflective coatings on the first light-transmitting reflector 3 and the second light-transmitting reflector 4 are both used to reflect the target wavelength, and the anti-reflection coatings on the first light-transmitting reflector 3 and the second light-transmitting reflector 4 are both used to transmit non-target light.

[0041] The reflectivity of the first light-transmitting reflective mirror 3 is greater than that of the second light-transmitting reflective mirror 4, so that the first external optical resonant cavity 5 formed by the first light-transmitting reflective mirror 3 and the gain chip 2 can achieve the best oscillation state of the gain chip 2, and the spectrum formed by the first external optical resonant cavity 5 is wider and has a higher peak value.

[0042] In some alternative embodiments: See Figure 1 and Figure 2 As shown, an embodiment of the present application provides an external cavity narrow linewidth laser component, in which a collimating lens 7 fixed on a substrate 1 is provided between the laser emitting end of the gain chip 2 and the first light-transmitting reflector 3 of the external cavity narrow linewidth laser component. The collimating lens 7 is used to collimate the outgoing light from the laser emitting end of the gain chip 2 and convert it into parallel light.

[0043] An etalon 8 fixed to substrate 1 is disposed between collimating lens 7 and first light-transmitting reflector 3. Etalon 8 is used to convert the parallel light coupled by collimating lens 7 into multi-peak, broad-spectrum parallel light with uniform free spectral range intervals. A filter 9 fixed to substrate 1 is disposed between first light-transmitting reflector 3 and second light-transmitting reflector 4. The passband range of filter 9 is consistent with the tuning range of second external optical resonant cavity 6 to suppress laser modes outside its passband range.

[0044] In some alternative embodiments: See Figure 1 and Figure 2 As shown, an embodiment of the present application provides an external cavity narrow linewidth laser assembly, in which an isolator 10 and a focusing lens 11 fixed to a substrate 1 are provided on the side of the second light-transmitting reflector 4 of the external cavity narrow linewidth laser assembly facing away from the first light-transmitting reflector 3. The isolator 10 is used to block the return light of the focusing lens 11 from returning to the second external optical resonant cavity 6 to avoid affecting the resonant performance of the second external optical resonant cavity 6. The focusing lens 11 is used to focus the collimated parallel light emitted by the gain chip 2 onto a collimating optical fiber (not shown in the figure).

[0045] In some alternative embodiments: See Figures 1 to 3As shown, an embodiment of the present application provides an external cavity narrow linewidth laser assembly, the collimating optical fiber of the external cavity narrow linewidth laser assembly is connected to a spectrometer (not shown in the figure), and a slideway (not shown in the figure) is provided on the substrate 1 for slidingly connecting the first light-transmitting reflector 3 and the second light-transmitting reflector 4, and the slideway extends along the laser emitting end direction of the gain chip 2.

[0046] The first and second light-transmitting reflective mirrors 3 and 4 slide on the slideways to adjust the cavity lengths of the first and second external optical resonant cavities 5 and 6, respectively. The spectrometer displays the spectral characteristics of different cavity lengths. The spectrometer detects and displays the spectrum formed by the cavity lengths of the first and second external optical resonant cavities 5 and 6 to determine the position of the first and second light-transmitting reflective mirrors 3 and 4 from the gain chip 2.

[0047] Also slidably connected to the slide are height adjusters (not shown in the figure) that are respectively connected to the first light-transmitting reflector 3 and the second light-transmitting reflector 4. The height adjusters are used to alternately adjust the heights of the first light-transmitting reflector 3 and the second light-transmitting reflector 4 so that the laser modes of the first external optical resonant cavity 5 and the second external optical resonant cavity 6 alternately formed by the first light-transmitting reflector 3 and the second light-transmitting reflector 4 are matched.

[0048] A heat sink 12 connected to the gain chip 2 is provided on the substrate 1. The gain chip 2 is attached to the heat sink 12 via eutectic bonding. The positive electrode on the surface of the gain chip 2 is electrically connected to one side of the heat sink 12 via a gold wire bond, while the negative electrode on the back of the gain chip 2 is electrically connected to the other side of the heat sink 12 via a bonding wire. The gain chip 2 is preferably a DFB laser, which significantly reduces the overall device cost. A housing (not shown) encapsulating the gain chip 2, the first light-transmitting reflector 3, and the second light-transmitting reflector 4 is provided on the substrate 1.

[0049] During testing or use, use two metal probes to connect the positive and negative poles of the gain chip 2 to the power supply, use the height adjuster to adjust the height of the first light-transmitting reflector 3 and the second light-transmitting reflector 4 to above the emitted light of the gain chip 2, and use a collimating optical fiber to collect light at the tail end of the substrate 1; fine-tune the distance between the collimating optical fiber and the gain chip 2, adjust the optical power to the maximum by observing the spectrum output by the spectrometer, and then fix the heat sink 12 with the gain chip 2 to complete the preliminary optical coupling.

[0050] After completing the initial optical coupling, use the height adjuster to first lower the first light-transmitting reflector 3 to a position close to the gain chip 2 to form the first external optical resonant cavity 5. Fine-tune the sliding of the first light-transmitting reflector 3 on the slide and observe the spectral pattern to ensure that the gain chip 2 reaches the best oscillation state and the oscillation peak matches the DFB chip peak.

[0051] Use the height adjuster to lift the first light-transmitting reflector 3 again, and lower the second light-transmitting reflector 4 to a position farther away from the gain chip 2. Fine-tune the second light-transmitting reflector 4 to slide on the slide to form a second external optical resonant cavity 6. Observe the spectrum pattern to ensure that the second external optical resonant cavity 6 matches the mode of the first external optical resonant cavity 5 and matches the peak of the DFB laser chip.

[0052] Finally, the height adjuster is used to lower the first light-transmitting reflector 3, and the first light-transmitting reflector 3 and the second light-transmitting reflector 4 are fine-tuned to find a stable state, thereby completing the coupling of the key parts.

[0053] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0054] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0055] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. An external cavity narrow linewidth laser assembly, characterized in that: include: A substrate (1), a gain chip (2) for emitting laser light being fixedly connected to the substrate (1), and a first light-transmitting reflector (3) and a second light-transmitting reflector (4) being sequentially spaced and arranged in the direction of the laser emitting end of the gain chip (2) being further connected to the substrate (1); The first light-transmitting reflector (3) and the gain chip (2) are spaced apart and together form a first external optical resonant cavity (5); the second light-transmitting reflector (4) and the first light-transmitting reflector (3) are spaced apart and together form a second external optical resonant cavity (6) with the gain chip (2).

2. The external cavity narrow linewidth laser assembly according to claim 1, characterized in that : The first light-transmitting reflective mirror (3) and the second light-transmitting reflective mirror (4) are both coated with a reflective film on one side close to the laser emitting end of the gain chip (2), and the first light-transmitting reflective mirror (3) and the second light-transmitting reflective mirror (4) are both coated with an anti-reflection film on one side away from the laser emitting end of the gain chip (2).

3. An external cavity narrow linewidth laser assembly according to claim 1 or 2, characterized in that : The reflectivity of the first light-transmitting reflector (3) is greater than the reflectivity of the second light-transmitting reflector (4), and the first light-transmitting reflector (3) and the second light-transmitting reflector (4) are both perpendicular to the direction of the laser emitting end of the gain chip (2).

4. An external cavity narrow linewidth laser assembly according to claim 1 or 2, characterized in that : A collimating lens (7) fixed on a substrate is provided between the laser emitting end of the gain chip (2) and the first light-transmitting reflector (3), and the collimating lens (7) is used to collimate the emitted light from the laser emitting end of the gain chip (2) into parallel light; An etalon (8) fixed on the substrate (1) is provided between the collimating lens (7) and the first light-transmitting reflector (3), and the etalon (8) is used to convert the parallel light coupled by the collimating lens (7) into multi-peak wide-spectrum parallel light with consistent free spectral range intervals.

5. An external cavity narrow linewidth laser assembly according to claim 1 or 2, characterized in that : A filter (9) fixed on the substrate (1) is provided between the first light-transmitting reflector (3) and the second light-transmitting reflector (4); the passband range of the filter (9) is consistent with the tuning range of the second external optical resonant cavity (6) to suppress laser modes outside its passband range.

6. An external cavity narrow linewidth laser assembly according to claim 1 or 2, characterized in that : An isolator (10) and a focusing lens (11) fixed on the substrate (1) are provided on the side of the second light-transmitting reflector (4) facing away from the first light-transmitting reflector (3); the isolator (10) is used to block the return light of the focusing lens (11) from returning to the second external optical resonant cavity (6); and the focusing lens (11) is used to focus the collimated parallel light emitted by the gain chip (2) onto the collimating optical fiber.

7. The external cavity narrow linewidth laser assembly according to claim 6, characterized in that : The collimating optical fiber is connected to a spectrometer, and a slideway for slidably connecting the first light-transmitting reflector (3) and the second light-transmitting reflector (4) is provided on the substrate (1), and the slideway extends in the direction of the laser emitting end of the gain chip (2); The first light-transmitting reflector (3) and the second light-transmitting reflector (4) slide on the slideway respectively to adjust the cavity lengths of the first external optical resonant cavity (5) and the second external optical resonant cavity (6), and the spectrometer displays spectral characteristics of different cavity lengths.

8. The external cavity narrow linewidth laser assembly according to claim 7, characterized in that : The slideway is also slidably connected to a height adjuster respectively connected to the first light-transmitting reflector (3) and the second light-transmitting reflector (4); the height adjuster is used to alternately adjust the heights of the first light-transmitting reflector (3) and the second light-transmitting reflector (4) so ​​as to match the laser modes of the first external optical resonant cavity (5) and the second external optical resonant cavity (6) alternately formed by the first light-transmitting reflector (3) and the second light-transmitting reflector (4).

9. An external cavity narrow linewidth laser assembly according to claim 1 or 2, characterized in that : A heat sink (12) connected to the gain chip (2) is provided on the substrate (1); the gain chip (2) is attached to the heat sink (12) by eutectic welding; the positive electrode on the surface of the gain chip (2) is connected to one side of the heat sink (12) by gold wire bonding; and the negative electrode on the back of the gain chip (2) is connected to the other side of the heat sink (12) by bonding.

10. An external cavity narrow linewidth laser assembly according to claim 1 or 2, characterized in that : The gain chip (2) is a DFB laser, and a housing for packaging the gain chip (2), a first light-transmitting reflector (3), and a second light-transmitting reflector (4) is provided on the substrate (1).

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