An integrated tunable external cavity ultra-narrow linewidth DBR laser

Abstract

The application provides an integrated tunable external cavity ultra-narrow linewidth DBR laser, relates to the technical field of lasers, and comprises a power supply part, a current source and a temperature control source; an ultra-narrow linewidth laser core, a DBR laser, an aspherical lens, a Si3N4 chip and a fiber microlens; and a measurement part, an optical isolator, a spectrometer, an acousto-optic modulator and a frequency spectrometer; part of output from the ultra-narrow linewidth laser core is isolated by the optical isolator to remove optical interference, and is divided into a first path and a second path, wherein the first path collects transmission spectrum after coupling through the Si3N4 chip at one end, the second path passes through the acousto-optic modulator, converts the optical signal into an electrical signal, and is connected to the frequency spectrometer through a single-mode optical fiber. The application has the beneficial effects of compact structure and integration, easy realization of effective external cavity feedback, increased potential detection distance, and narrow linewidth laser generated by the application, which can replace optically pumped solid-state lasers to be applied to spatial coherent light communication.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and more specifically, to an integrated tunable external cavity ultra-narrow linewidth DBR laser. Background Technology

[0002] With the development and advancement of optical information technology and the increasing demand for communication bandwidth, optical networks are evolving from static networks with a single transmission function to dynamic networks with both transmission and routing capabilities. For narrow-linewidth lasers, solid-state, fiber, and semiconductor lasers are the three most commonly used types. Solid-state and fiber lasers have relatively large volumes and longer resonant cavity lengths, meaning longer photon lifetimes and thus easier achievement of good phase / frequency noise performance. However, solid-state and fiber lasers inevitably have larger sizes and weights, and their manufacturing and packaging costs are very high. Furthermore, they all require semiconductor lasers for optical pumping. Tunable semiconductor lasers, with their chip-level size, flexible multi-wavelength selective lasing characteristics, and direct electrical pumping capabilities, stand out from many other types of lasers and will become important components in future optical networks.

[0003] Optical feedback is currently the main method for achieving narrow linewidths in semiconductor lasers. To increase the effective length of the laser resonator and thus reduce the linewidth, wavelength-sensitive optical components such as gratings, mirrors, and fiber waveguides are used as external reflectors to reflect the emitted laser light. However, the integration of external optical components makes the laser system overly complex. Furthermore, the high environmental stability requirements of the external feedback system and the resulting lack of compactness lead to poor overall laser reliability. Summary of the Invention

[0004] The purpose of this invention is to provide an integrated tunable external cavity ultra-narrow linewidth DBR laser to improve the aforementioned problems. To achieve this objective, the technical solution adopted by this invention is as follows: This application provides an integrated tunable external cavity ultra-narrow linewidth DBR laser, comprising: The power supply section, including a current source and a temperature control source, is used to power the integrable narrow-linewidth laser. The core of the ultra-narrow linewidth laser includes a DBR laser, an aspherical lens, a Si3N4 chip, and a fiber microlens. The output port of the DBR laser is connected to the input port of the aspherical lens. The generated beam is focused onto the Si3N4 chip after passing through the aspherical lens. The output port of the Si3N4 chip is connected to the input port of the fiber microlens. The measurement section includes an optical isolator, a spectrometer, an acousto-optic modulator, and a spectrum analyzer. The output port of the fiber optic microlens is connected to the input port of the optical isolator. The output port of the optical isolator is connected to the input port of the spectrum analyzer via the spectrometer and the acousto-optic modulator. The portion output from the core of the ultra-narrow linewidth laser is separated into a first path and a second path after optical interference is isolated by the optical isolator. One end of the first path collects the transmission spectrum after coupling through the Si3N4 chip. The second path passes through the acousto-optic modulator, converts the optical signal into an electrical signal, and connects to the spectrum analyzer through a single-mode fiber.

[0005] Preferably, the DBR laser includes a gain region, a phase modulation region, and a DBR region, wherein the output port of the gain region is connected to the input port of the phase modulation region, the output port of the phase modulation region is connected to the input port of the DBR region, and the output port of the DBR region is connected to the input port of the aspherical lens. The laser beam, generated sequentially through the gain region, phase modulation region, and DBR region, is coupled into the Si3N4 chip through a 1.5mm aspherical lens. A tunable dual micro-ring resonator is integrated in the micro-ring and enters from the left end face of the chip. Rayleigh scattering is generated along the fiber axis in the high-Q Si3N4 micro-ring resonator, either forward or backward. The backscattered light is fed back into the DBR laser through the aspherical lens, thus forming an external cavity feedback path. Finally, an ultra-narrow linewidth laser output is obtained under the drive of the current source.

[0006] Preferably, it is determined whether the center resonant frequency generated in the tunable dual microring resonator reaches the isolated frequency of the DBR laser. If it does, the electrodes of the dual microring resonator are adjusted to adjust the feedback ratio. If it does not reach the required frequency, no adjustment is needed. The feedback ratio is the effective optical feedback efficiency generated in the tunable dual microring resonator.

[0007] Preferably, after the laser beam passes through the tunable dual microring resonator, it enters a self-injection locked state by adjusting the phase junction current and the DBR junction current.

[0008] Preferably, the feedback ratio is divided into five intervals, from low to high: the first interval, the second interval, the third interval, the fourth interval, and the fifth interval. When the feedback ratio exceeds 10%, the DBR laser enters the fifth interval, and the output laser mode is a stable single longitudinal mode with a narrow linewidth. The formula for calculating the center resonant frequency using the Lorentz function is as follows:

[0009] In the formula, ω f Where Λ is the resonant frequency and Λ is the half-maximum linewidth. The center resonant frequency of the half-maximum spectral linewidth Λ. For complex units, ω is the angular frequency.

[0010] Preferably, the dynamic response of the DBR laser in the self-injection locked state is calculated as follows:

[0011] In the formula, and These represent the isolated frequency and the operating frequency of the output mode of the laser diode, respectively. For external round-trip time, ω f Where Λ is the resonant frequency and Λ is the half-maximum linewidth. For effective optical feedback efficiency, The arctangent of the linewidth enhancement factor; and

[0012] Indicates effective optical feedback efficiency. Indicates the operating frequency of the output mode. For external round-trip time, For feedback rate, Linewidth enhancement factor This indicates the external phase delay, without loss. It can be used This indicates that Λ represents the half-maximum spectral linewidth. The center resonant frequency.

[0013] Preferably, the power supply section consists of two temperature control sources and one current source; Two temperature control sources control the temperature of the DBR laser and the Si3N4 chip respectively, while a current source powers the DBR laser.

[0014] Preferably, the spectrometer is model AQ6317C, the spectrum analyzer is model R&SFSW67; and the output port of the fiber microlens is a single-mode fiber APC interface.

[0015] The beneficial effects of this invention are as follows: This invention uses DBR output, which is a single longitudinal mode output. The optical power is mainly concentrated on this single longitudinal mode, and there is no strong FP mode caused by coating. This reduces the mode switching problem caused by mode competition and has the characteristic of wavelength tunability. The lasing wavelength is easy to align with the reflection wavelength of the fiber grating, and it is easier to achieve effective external cavity feedback.

[0016] The device used in this invention is small and compact, and easy to integrate. The narrow linewidth or low-frequency noise it generates can provide a high coherence range for the lidar source, increasing the potential detection range. The narrow linewidth laser it generates can replace optically pumped solid-state lasers for spatial coherent optical communication applications.

[0017] This invention utilizes linear frequency modulation based on a two-dimensional phase MRR tuning method, achieving a continuous wavelength tuning range of 1543nm-1550nm, a side-mode rejection ratio of up to 34dB, and an inherent linewidth of 5kHz during static operation. Furthermore, its compact and integrable structure allows for further development in fields such as fiber optic sensing and lidar systems.

[0018] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the integrated tunable external cavity ultra-narrow linewidth DBR laser device described in an embodiment of the present invention; Figure 2 This is a schematic diagram of the cold cavity characteristics within the tunable range of the integrated tunable external cavity ultra-narrow linewidth DBR laser described in this embodiment of the invention; Figure 3 This is a schematic diagram of the PI curve of the integrated tunable external cavity ultra-narrow linewidth DBR laser described in this embodiment of the invention; Figure 4 This is a schematic diagram of wavelength tuning for the integrated tunable external cavity ultra-narrow linewidth DBR laser described in this embodiment of the invention; Figure 5 This is a schematic diagram of the external cavity laser spectrum of the integrated tunable external cavity ultra-narrow linewidth DBR laser described in this embodiment of the invention; Figure 6 This is a schematic diagram of the linewidth test results of the integrated tunable external cavity ultra-narrow linewidth DBR laser described in this embodiment of the invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] Example 1:

[0024] This embodiment provides an integrated tunable external cavity ultra-narrow linewidth DBR laser.

[0025] See Figures 1-6 As shown in the figure, an integrated tunable external cavity ultra-narrow linewidth DBR laser is illustrated, comprising: The power supply section, including a current source and a temperature control source, is used to power the integrable narrow-linewidth laser. The core of the ultra-narrow linewidth laser includes a DBR laser, an aspherical lens, a Si3N4 chip, and a fiber microlens. The output port of the DBR laser is connected to the input port of the aspherical lens. The generated beam is focused onto the Si3N4 chip after passing through the aspherical lens. The output port of the Si3N4 chip is connected to the input port of the fiber microlens. The measurement section includes an optical isolator, a spectrometer, an acousto-optic modulator, and a spectrum analyzer. The output port of the fiber optic microlens is connected to the input port of the optical isolator. The output port of the optical isolator is connected to the input port of the spectrum analyzer via the spectrometer and the acousto-optic modulator. The portion output from the core of the ultra-narrow linewidth laser is separated into a first path and a second path after optical interference is isolated by the optical isolator. One end of the first path collects the transmission spectrum after coupling through the Si3N4 chip. The second path passes through the acousto-optic modulator, converts the optical signal into an electrical signal, and connects to the spectrum analyzer through a single-mode fiber.

[0026] It should be noted that this invention consists of a power supply section, an ultra-narrow linewidth laser core, and a measurement section, collectively constituting a tunable integrated semiconductor laser device based on the coupling of a DBR laser and a high-Q Si3N4 microring resonator (MRR). The ultra-narrow linewidth laser core comprises three DBR laser sections, each powered by a current source (DP2031). The generated beam is focused onto the microring through a 1.5mm diameter aspherical lens. This hybrid laser source employs end-face coupling, and the output of the integrated waveguide is guided by an aspherical lens and a microlens fiber. This invention has a small and compact structure, is easy to integrate, and the main body is only 9mm in size.

[0027] Specifically, the measurement section consists of an optical isolator, a spectrometer, a spectrum analyzer, an acousto-optic modulator, and a 40km delay fiber. The laser output, after being isolated from optical interference by the isolator, is split into high-power and low-power paths by a 2:8 beam splitter. The low-power path receives the MRR transmission spectrum from the spectrometer (AQ6317C). The high-power path, after passing through the acousto-optic modulator, performs a fixed frequency shift on the optical signal, passes through the 40km delay fiber, and then connects to the spectrum analyzer (R&SFSW67) via a PD. The laser linewidth can be determined using the delay self-heterodyne method.

[0028] It should be noted that the power supply consists of two TEC temperature control sources (Newport-LDC-3724C) and one current source (DP2031). The two temperature control sources respectively control the temperature of the three DBR lasers and the Si3N4 chip to improve the stability of the device, while the current source powers the three DBR lasers.

[0029] The tunable integrated semiconductor laser device of this invention comprises four parts (semiconductor laser chip, coupling lens, high-Q Si3N4 microring, and microlens fiber section). Each of these four parts is supported by a precision adjustment frame with a resolution of 0.5 micrometers, thereby enabling direct high-precision chip alignment. Overall, compared with traditional tunable lasers, the structure of this invention has significant advantages in terms of compactness and high integration.

[0030] Therefore, the DBR outputs a single longitudinal mode, and the optical power is mainly concentrated in this single longitudinal mode. It avoids the strong FP mode caused by coating limitations, reducing mode switching problems caused by mode competition. It also has wavelength tunable characteristics, making it easy to align the lasing wavelength with the reflection wavelength of the fiber grating, thus facilitating effective external cavity feedback. Figure 2 The image shows the cold cavity characteristics of the Si3N4 microring resonator within the tunable range. It can be seen that the quality factor Q is greater than 10 for all cases. 8 Cold cavity spectrometry can provide the center wavelength of the external cavity laser in different channels, making it easy to switch.

[0031] Specifically, the DBR laser includes a gain region, a phase modulation region, and a DBR region, wherein the output port of the gain region is connected to the input port of the phase modulation region, the output port of the phase modulation region is connected to the input port of the DBR region, and the output port of the DBR region is connected to the input port of the aspherical lens. The laser beam, generated sequentially through the gain region, phase modulation region, and DBR region, is coupled into the Si3N4 chip through a 1.5mm aspherical lens. A tunable dual micro-ring resonator is integrated in the micro-ring and enters from the left end face of the chip. Rayleigh scattering is generated along the fiber axis in the high-Q Si3N4 micro-ring resonator, either forward or backward. The backscattered light is fed back into the DBR laser through the aspherical lens, thus forming an external cavity feedback path. Finally, an ultra-narrow linewidth laser output is obtained under the drive of the current source.

[0032] It should be noted that the entire operation of the external cavity laser is as follows: A three-segment DBR laser (comprising three regions: gain region, phase modulation region, and DBR region) is used. Driven by an adjustable precision current source (DP2031), an initial laser beam is generated. This beam passes through a 1.5mm diameter aspherical lens and is precisely coupled into a Si3N4 microring, entering from the left end face of the chip. In the high-Q MRR, due to the high-Q effect, the intensity of the optical mode in the MRR cavity can be thousands of times higher than the laser beam intensity, thus exciting strong backpropagating Rayleigh scattering light. The backpropagating scattered light passes through the aspherical lens and is fed back into the three-segment DBR laser, thus forming an external cavity feedback scheme with a main body size of only 9mm. Figure 3 and Figure 4 As shown, the PI curve and wavelength tuning diagram of the DBR laser demonstrate that the laser's wavelength can be continuously tuned at 1550nm.

[0033] It should be noted that, regarding tunability, because the three-segment DBR has a distributed Bragg reflector, and the high-Q MRR also constitutes a feedback cavity, the coexistence of the two cavities will result in multiple resonant modes throughout the system.

[0034] By carefully adjusting the phase region and active gain region of the DBR laser, and combining the vernier effect of the dual-cavity design, the multimode output modes of the DBR can be compressed into a single dominant mode excitation; the integrated waveguide is used for output guidance by an aspherical lens and a microlens fiber.

[0035] Further, it is determined whether the center resonant frequency generated in the tunable dual microring resonator reaches the isolated frequency of the DBR laser. If it does, the electrodes of the dual microring resonator are adjusted to adjust the feedback ratio. If it does not reach the required frequency, no adjustment is needed. The feedback ratio is the effective optical feedback efficiency generated in the tunable dual microring resonator.

[0036] Furthermore, after passing through the tunable dual-microring resonator, the laser beam enters a self-injection locked state by adjusting the phase junction current and the DBR junction current. For example... Figure 5 As shown, Figure 5 The image shows the spectrum of the external cavity laser. After passing through the micro-ring resonator, the laser enters a self-injection locked state by adjusting the phase gate current and the DBR gate current. The side modes of the laser are well suppressed, and the spectrum shows a very obvious single peak. The side mode suppression ratio (SMSR) is 34 dB.

[0037] Furthermore, the feedback ratio is divided into five intervals, from low to high: the first interval, the second interval, the third interval, the fourth interval, and the fifth interval. When the MRR center resonant frequency is close to the isolated frequency of the DBR laser, the feedback intensity can be increased by adjusting the MRR electrode.

[0038] When the feedback ratio exceeds 10%, the DBR laser enters the fifth interval, and the output laser mode is a stable single longitudinal mode with a narrow linewidth. In this state, the role of MRR in the laser can be simplified to two parameters: the half-maximum linewidth (FWHM) Λ, the center resonant frequency, and the resonant frequency ω. f , defined as the frequency offset from that of the isolated laser. The formula for calculating the center resonant frequency, expressed using the Lorentz function, is as follows:

[0039] In the formula, ω f Where Λ is the resonant frequency and Λ is the half-maximum linewidth. The center resonant frequency of the half-maximum spectral linewidth Λ. For complex units, ω is the angular frequency.

[0040] Furthermore, the dynamic response of the DBR laser in the self-injection locked state is calculated as follows:

[0041] In the formula, and These represent the isolated frequency and the operating frequency of the output mode of the laser diode, respectively. For external round-trip time, ω f Where Λ is the resonant frequency and Λ is the half-maximum linewidth. For effective optical feedback efficiency, The arctangent of the linewidth enhancement factor; and

[0042] Indicates effective optical feedback efficiency. Indicates the operating frequency of the output mode. For external round-trip time, For feedback rate, Linewidth enhancement factor This indicates the external phase delay, without loss. It can be used This indicates that Λ represents the half-maximum spectral linewidth. The center resonant frequency.

[0043] Specifically, for the laser proposed in this invention, the phase thermoelectric electrode and the MRR thermoelectric electrode can respectively make and Detuning. Lock-in state is the result of phase and MRR electrode synchronization tuning, which can be achieved by solving the equation... and Explain the relationship between them. For example... Figure 6 The image shows the linewidth test results of the external cavity laser. The linewidth was determined to be 5 kHz using the delayed self-heterodyne method. Future research can further reduce the laser linewidth by increasing the quality factor Q.

[0044] It should be noted that this structure not only enables single-mode selection, but also allows for narrowing of the linewidth due to the introduction of the external cavity structure.

[0045] Furthermore, the power supply section consists of two temperature control sources and one current source; Two temperature control sources control the temperature of the DBR laser and the Si3N4 chip respectively, while a current source powers the DBR laser.

[0046] Furthermore, the spectrometer is model AQ6317C, and the spectrum analyzer is model R&SFSW67.

[0047] Furthermore, the output port of the fiber microlens is a single-mode fiber APC interface.

[0048] In summary, the DBR outputs a single longitudinal mode, reducing mode hopping problems caused by mode competition; it has the characteristic of wavelength tunability, and the lasing wavelength is easily aligned with the reflection wavelength of the fiber grating, making it easier to achieve effective external cavity feedback; the device is small and compact, and easy to integrate; the generated narrow linewidth or low-frequency noise can provide a high coherence range for the lidar source, increasing the potential detection distance; the narrow linewidth laser it generates can replace optically pumped solid-state lasers for spatial coherent optical communication applications.

[0049] It should be noted that the specific manner in which each module performs its operation in the apparatus described in the above embodiments has been described in detail in the embodiments of the method, and will not be elaborated here.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0051] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An integrated tunable external cavity ultra-narrow linewidth DBR laser, characterized in that, include: The power supply section, including a current source and a temperature control source, is used to power the integrable narrow-linewidth laser. The core of the ultra-narrow linewidth laser includes a DBR laser, an aspherical lens, a Si3N4 chip, and a microlens fiber. The output port of the DBR laser is connected to the input port of the aspherical lens. The generated beam is focused onto the Si3N4 chip after passing through the aspherical lens. The output port of the Si3N4 chip is connected to the input port of the microlens fiber. The measurement section includes an optical isolator, a spectrometer, an acousto-optic modulator, and a spectrum analyzer. The output port of the microlens fiber is connected to the input port of the optical isolator, and the output port of the optical isolator is connected to the input port of the spectrum analyzer through the spectrometer and the acousto-optic modulator in sequence. The output from the core of the ultra-narrow linewidth laser is separated from optical interference by an optical isolator and then divided into a first path and a second path. One end of the first path collects the transmission spectrum after coupling through the Si3N4 chip, while the second path passes through an acousto-optic modulator to perform fixed frequency shifting of the optical signal and then passes through a 40km delay fiber. The DBR laser includes a gain region, a phase modulation region, and a DBR region, wherein the output port of the gain region is connected to the input port of the phase modulation region, the output port of the phase modulation region is connected to the input port of the DBR region, and the output port of the DBR region is connected to the input port of the aspherical lens. The laser beam, generated sequentially through the gain region, phase modulation region, and DBR region, is coupled into the Si3N4 chip through a 1.5mm aspherical lens. A tunable dual-micro-ring resonator is integrated within the micro-ring and enters from the left end face of the chip. Rayleigh scattering along the fiber axis is generated in the high-Q Si3N4 micro-ring resonator, either forward or backward. The backscattered light passes through the aspherical lens and is fed back into the DBR laser, thus forming an external cavity feedback path. Finally, an ultra-narrow linewidth laser output is obtained under the drive of a current source. Specifically, it is determined whether the center resonant frequency generated in the tunable dual microring resonator reaches the isolated frequency of the DBR laser. If it does, the electrodes of the dual microring resonator are adjusted to adjust the feedback ratio. If it does not reach the isolated frequency, no adjustment is required. The feedback ratio is the effective optical feedback efficiency generated in the tunable dual microring resonator. The feedback ratio is divided into five intervals, from low to high: the first interval, the second interval, the third interval, the fourth interval, and the fifth interval. When the feedback ratio exceeds 10%, the DBR laser enters the fifth interval, and the output laser mode is a stable single longitudinal mode with a narrow linewidth. The formula for calculating the center resonant frequency using the Lorentz function is as follows: In the formula, ω f Where Λ is the resonant frequency and Λ is the half-maximum linewidth. The center resonant frequency of the half-maximum spectral linewidth Λ. For complex units, ω is the angular frequency.

2. The integrated tunable external cavity ultra-narrow linewidth DBR laser according to claim 1, characterized in that, After passing through the tunable dual microring resonator, the laser beam enters a self-injection locked state by adjusting the phase junction current and the DBR junction current.

3. The integrated tunable external cavity ultra-narrow linewidth DBR laser according to claim 2, characterized in that, The dynamic response of the DBR laser under the self-injection locked state is calculated as follows: In the formula, and These represent the isolated frequency and the operating frequency of the output mode of the laser diode, respectively. For external round-trip time, ω f Where Λ is the resonant frequency and Λ is the half-maximum linewidth. For effective optical feedback efficiency, The arctangent of the linewidth enhancement factor; and Indicates effective optical feedback efficiency. Indicates the operating frequency of the output mode. For external round-trip time, For feedback rate, Linewidth enhancement factor This indicates the external phase delay, assuming no loss. It can be used This indicates that Λ represents the half-maximum spectral linewidth. The center resonant frequency.

4. The integrated tunable external cavity ultra-narrow linewidth DBR laser according to claim 1, characterized in that, The power supply section consists of two temperature control sources and one current source; Two temperature control sources control the temperature of the DBR laser and the Si3N4 chip respectively, while a current source powers the DBR laser.

5. The integrated tunable external cavity ultra-narrow linewidth DBR laser according to claim 1, characterized in that, The spectrometer is model AQ6317C, and the spectrum analyzer is model R&SFSW67.

6. The integrated tunable external cavity ultra-narrow linewidth DBR laser according to claim 1, characterized in that, The output port of the microlens fiber is a single-mode fiber APC interface.

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