Adjusting device and method for tuning mirror in external cavity tunable laser source

Abstract

The application discloses an adjusting device and method of a tuning mirror in an external cavity tunable laser source, wherein the external cavity tunable laser source comprises a gain chip, a shaping lens, a frequency selection device and a tuning mirror; the adjusting device comprises a beam splitting cube, a photosensitive element and a beam quality analyzer; the beam splitting cube is arranged between the frequency selection device and the beam quality analyzer, and the photosensitive element is arranged on one side of the beam splitting cube; the beam splitting cube is used for separating the light beam output by the external cavity tunable laser source, the photosensitive element is used for feeding back the current state of the tuning mirror, and the beam quality analyzer is used for capturing the shape and position of the 0th order resonant output light spot of the external cavity tunable laser source. The adjusting device and method disclosed by the application can realize the rapid determination of the optimal state of the tuning mirror in the external cavity tunable laser source, reduce the adjustment cost and promote the rapid development of the external cavity tunable laser source industry.

Description

Technical Field

[0001] This invention relates to an adjustment device and method for a tuning mirror in an external cavity tunable laser source. Background Technology

[0002] External cavity tunable laser sources, due to their outstanding advantages such as single longitudinal mode, narrow linewidth, continuously tunable output wavelength, and low phase noise, have been widely used in high-speed coherent optical communication networks based on high-order optical modulation schemes, fiber-optic three-dimensional shape sensing with cross-correlation frequency domain decoupling, trace gas detection with linear frequency sweep, and autonomous driving. However, in the resonant spectrum output process of traditional external cavity tunable laser sources, the realization of wide-range, narrow-linewidth, continuously variable wavelength laser output heavily depends on the rapid adjustment of the tuning mirror to its optimal state.

[0003] The adjustment of the tuning mirror state in a traditional external cavity tunable laser source is typically achieved by measuring the spectral morphology (narrowing and mode), wavelength morphology (jumps and noise floor), and coupled output power of the external cavity tunable laser source. This involves illuminating the semiconductor gain chip in the external cavity tunable laser source. The light emitted from the semiconductor gain chip passes sequentially through a shaping lens and a blazed grating before being incident on the tuning mirror surface. The light fed back from the tuning mirror returns along the original path to the active region of the semiconductor gain chip. The zero-order light, amplified by the active region, is then guided into a spectrometer / wavelength meter / power meter. The tuning mirror state is adjusted based on the characteristics of the light signal measured in the spectrometer / wavelength meter / power meter until the spectral width is significantly compressed, the wavelength value tends to stabilize, and the radiated power is better than expected. The tuning mirror state is then fixed, and the tuning mirror assembly in the external cavity tunable laser source is complete. However, the above-mentioned assembly and adjustment methods and devices have the following drawbacks: the external cavity tunable laser source contains diffraction elements, and the beam quality will deteriorate after passing through the diffraction elements, affecting the fiber coupling efficiency. It is difficult to transmit the adjustment state of the tuning mirror efficiently and accurately, and the adjustment process is inefficient and costly. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an adjustment device and method for a tuning mirror in an external cavity tunable laser source, thereby achieving rapid determination of the optimal state of the tuning mirror in the external cavity tunable laser source and reducing adjustment costs.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] An adjustment device for a tuning mirror in an external cavity tunable laser source is disclosed. The external cavity tunable laser source includes a gain chip, a shaping lens, a frequency selection device, and a tuning mirror. The adjustment device includes a beam splitter cube, a photosensitive element, and a beam quality analyzer. The beam splitter cube is disposed between the frequency selection device and the beam quality analyzer, and the photosensitive element is disposed on one side of the beam splitter cube. The beam splitter cube is used to separate the beam output from the external cavity tunable laser source. The photosensitive element is used to provide feedback on the current state of the tuning mirror. The beam quality analyzer is used to capture the shape and position of the zeroth order resonant output beam spot of the external cavity tunable laser source.

[0007] A method for adjusting a tuning mirror in an external cavity tunable laser source, employing an adjustment device for a tuning mirror in an external cavity tunable laser source as described above, includes the following steps:

[0008] Step 1: Activate the gain chip and preheat it;

[0009] Step 2: Adjust the position and orientation of the beam quality analyzer and record the beam pattern emitted from the gain chip after the 0th order diffraction by the frequency selection device;

[0010] Step 3: Determine whether the light spot collected by the beam quality analyzer is centered on the beam quality analyzer. If it is not centered, return to step 2 until the light spot is centered.

[0011] Step 4: Place the beam splitter cube in front of the beam quality analyzer and adjust its orientation to ensure that the shape of the light spot received by the beam quality analyzer does not change significantly.

[0012] Step 5: Place the tuning mirror in the external cavity tunable laser source and place the photosensitive element on one side of the beam splitter cube. The external cavity resonant light is split into two beams of different intensities by the beam splitter cube. One beam is incident perpendicularly on the surface of the photosensitive element. Adjust the state of the tuning mirror according to the red flashing intensity displayed on the surface of the photosensitive element until the red flashing intensity suddenly increases.

[0013] Step 6: Based on the spot shape of the other incident beam onto the beam quality analyzer, finely adjust the tuning mirror until the spot shape collected by the beam quality analyzer is similar to the spot shape collected without tuning. At this point, the tuning mirror has reached its optimal state. Fix the tuning mirror to finish.

[0014] In the above scheme, the preheating time in step 1 is 30 minutes.

[0015] Through the above technical solution, the adjustment device and method for the tuning mirror in an external cavity tunable laser source provided by the present invention have the following beneficial effects:

[0016] This invention leverages the sensitivity of the resonant output intensity of an external cavity tunable laser source to changes in the state of the tuning mirror. By visually analyzing the intensity of light obtained during testing, it achieves rapid locking of the optimal state of the tuning mirror within the external cavity tunable laser source. This improves the wavelength stability and side-mode suppression ratio of the external cavity tunable laser source output, solving the problems of the complexity of determining the optimal state of the tuning mirror using traditional methods such as spectral / wavelength / power / auxiliary visible light measurements, the high cost of the entire testing system, and the significant impact of fiber coupling efficiency on test results. It enables rapid determination of the optimal state of the tuning mirror in an external cavity tunable laser source, providing advanced testing instruments for fields such as intelligent high-speed coherent network reconfigurable transmission, fiber optic three-dimensional shape frequency domain sensing, high-precision gas spectral measurement, and autonomous driving. Furthermore, it expands the application scope of external cavity tunable laser sources, increasing their application scenarios and promoting the rapid development of the external cavity tunable laser source industry. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0018] Figure 1 This is a schematic diagram of an adjustment device for a tuning mirror in an external cavity tunable laser source disclosed in an embodiment of the present invention;

[0019] Figure 2 This is a schematic flowchart of a method for adjusting a tuning mirror in an external cavity tunable laser source disclosed in an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0021] This invention provides an adjustment device for a tuning mirror in an external cavity tunable laser source, such as... Figure 1 As shown, the external cavity tunable laser source includes a gain chip, a shaping lens, a frequency selection device, and a tuning mirror.

[0022] The gain chip is a single-angle gain chip used to generate the initial light intensity of the cavity, with a typical emission angle of 26.5°.

[0023] Shaping lenses are used to shape and collimate the elliptical beam emitted from gain chips; typically, they are molded aspherical lenses.

[0024] Frequency-selective devices are used for dispersion mode selection, typically blazed gratings.

[0025] A tuning mirror forms the highly reflective end face of the external cavity tunable laser source resonator, typically a gold-plated reflector.

[0026] The adjustment device includes a beam splitter cube, a photosensitive element, and a beam quality analyzer; the beam splitter cube is positioned between the frequency selection device and the beam quality analyzer, and the photosensitive element is positioned on one side of the beam splitter cube.

[0027] A beam splitter cube is used to separate the beam output from an external cavity tunable laser source, with a typical splitting ratio of 80:20.

[0028] A photosensitive element is used to provide feedback on the current state of the tuning mirror.

[0029] A beam quality analyzer is used to capture the shape and position of the 0th order resonant output beam spot of an external cavity tunable laser source.

[0030] A method for adjusting a tuning mirror in an external cavity tunable laser source, employing the aforementioned adjustment device for the tuning mirror in an external cavity tunable laser source, such as... Figure 2 As shown, it includes the following steps:

[0031] Step 1: Activate the gain chip and preheat for 30 minutes;

[0032] Step 2: Adjust the position and orientation of the beam quality analyzer, and record the beam pattern emitted by the gain chip after the 0th order diffraction of the frequency selection device; record the common height of the spatial optical path of the radiation output to ensure that the test position of the beam quality analyzer in the optical path is correct.

[0033] Step 3: Determine whether the light spot collected by the beam quality analyzer is centered on the beam quality analyzer. If it is not centered, return to step 2 until the light spot is centered.

[0034] Step 4: Place the beam splitter cube in front of the beam quality analyzer and adjust its orientation to ensure that the shape of the light spot received by the beam quality analyzer does not change significantly; this confirms that the components in the spatial optical path are at common height and the beam transmission is unobstructed.

[0035] Step 5: Place the tuning mirror in the external cavity tunable laser source and place the photosensitive element on one side of the beam splitter cube. The external cavity resonant light is split into two beams of different intensities by the beam splitter cube. One beam is incident perpendicularly on the surface of the photosensitive element. Adjust the state of the tuning mirror according to the red flashing intensity displayed on the surface of the photosensitive element until the red flashing intensity suddenly increases. This means that the internal and external cavity modes are matched at this time, and resonant laser radiation output occurs. The laser output causes the flashing intensity of the photosensitive element to increase. If the strong flashing state of the photosensitive element is maintained, the degree of matching between the internal and external cavity modes is the highest, that is, the position of the tuning mirror is optimal.

[0036] Step 6: Based on the spot shape of the other incident beam onto the beam quality analyzer, finely adjust the tuning mirror until the spot shape collected by the beam quality analyzer is similar to the spot shape collected without tuning. This indicates that the external resonance mode and the radiation output mode of the internal optical field caused by the installation of the tuning mirror share the same optical path. At this point, the tuning mirror has reached its optimal state. Fix the tuning mirror and the process is complete.

[0037] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. 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 invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for adjusting a tuning mirror in an external cavity tunable laser source, using a tuning mirror adjustment device for an external cavity tunable laser source, the external cavity tunable laser source comprising a gain chip, a shaping lens, a frequency selection device and a tuning mirror; characterized in that, The adjusting device comprises a beam splitting cube, a photosensitive element and a beam quality analyzer; the beam splitting cube is arranged between the frequency selection device and the beam quality analyzer, and the photosensitive element is arranged on one side of the beam splitting cube; the beam splitting cube is used for splitting the light beam output by the external cavity tunable laser source, the photosensitive element is used for feeding back the current state of the tuning mirror, and the beam quality analyzer is used for capturing the shape and position of the 0th order resonance output light spot of the external cavity tunable laser source; The adjusting method comprises the following steps: Step 1: activate the gain chip and preheat; Step 2: adjust the position and posture of the beam quality analyzer, and record the light spot shape of the gain chip after the 0th order diffraction of the frequency selection device; Step 3: determine whether the light spot collected by the beam quality analyzer is in the center of the beam quality analyzer, if not, return to step 2 until the light spot is in the center; Step 4: place the beam splitting cube in front of the beam quality analyzer, adjust the posture of the beam splitting cube, and ensure that the light spot shape received by the beam quality analyzer has no obvious change; Step 5: place the tuning mirror in the external cavity tunable laser source, and place the photosensitive element on one side of the beam splitting cube, the external cavity resonance light is split into two beams with different intensities by the beam splitting cube; one beam is vertically incident on the surface of the photosensitive element, the state of the tuning mirror is adjusted according to the red flicker intensity displayed on the surface of the photosensitive element until the red flicker intensity suddenly increases; Step 6: according to the light spot shape of the other beam incident on the beam quality analyzer, the tuning mirror is slightly adjusted until the light spot shape collected by the beam quality analyzer is similar to the light spot shape collected when the tuning mirror is not tuned, at this time, the tuning mirror reaches the best state, the tuning mirror is fixed, and the process is ended.

2. The method of claim 1, wherein the tuning mirror is a mirror in an external cavity tunable laser source. The preheating time in step 1 is 30 min.

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