Method, device and equipment for mode-hopping wavelength tuning of tunable laser

Abstract

The present invention relates to the technical field of tunable semiconductor lasers and discloses a mode-hopping wavelength tuning method, device and equipment for a tunable laser. The method comprises the following steps: scanning a reflection region current of a tunable laser based on a preset scanning strategy to obtain a plurality of step data; extracting valid step data and dividing data belonging to the same wavelength tuning region into a group; fitting the midpoints of each valid data set to obtain a smooth wavelength tuning path, scanning and verifying, and screening characteristic points; performing positive and negative phase current loading at each characteristic point to obtain a phase region tuning curve and retrieve a target wavelength; and in each smooth wavelength tuning path, splicing all target wavelengths end to end to obtain an initial current tuning curve, obtaining a target current tuning curve by using an interpolation method, constructing a current tuning curve over a full wavelength range as a wavelength current lookup table, and implementing a mode-hopping wavelength tuning method for a tunable laser.

Description

Technical Field

[0001] The present invention relates to the technical field of tunable semiconductor lasers, and in particular to a method, device and equipment for tuning the wavelength of a tunable laser without mode hopping. Background Art

[0002] After more than sixty years of development, semiconductor lasers have made great progress in terms of wavelength tuning range, output power level, linewidth, etc. With the development of application research, it covers a wide range of fields, including optical communications, fiber optic sensing, spectral analysis, etc. Among them, fiber optic sensing has put forward more stringent requirements on the tuning performance of tunable lasers. Currently, the development along the direction of optoelectronic integration is multi-electrode controlled tunable semiconductor lasers, which can be divided into external cavity tunable lasers, distributed feedback lasers and distributed Bragg reflector (DBR) lasers according to the structure. In particular, the modulated grating Y-branched (MG-Y) laser branched from the DBR laser has a wider wavelength coverage range, greater output power and higher side mode suppression ratio, and is a high-quality light source for low-cost and high-precision fiber optic sensing applications. The MG-Y laser is mainly composed of a left reflection zone, a right reflection zone and a phase zone. The left and right reflection zones have comb reflection spectra with different intervals in wavelength. By changing its injection current I LR , I PH A certain peak wavelength output can be achieved. The function of the phase zone is to change the laser longitudinal mode resonant wavelength. PH The wavelength tuning of the laser is controlled by the three currents mentioned above, which can achieve accurate output of any wavelength within the tuning range.

[0003] In practical applications, a wavelength-current lookup table (LUT) must be constructed for the laser to characterize the corresponding relationship between wavelength and current combinations. Currently, existing technologies offer a variety of tuning methods, but laser tuning based on the wavelength-current LUT is unstable. Mode hopping is often observed between non-adjacent operating points in the LUT, resulting in unstable laser tuning. Summary of the Invention

[0004] To this end, the technical problem to be solved by the present invention is to overcome the problem in the prior art that when a tunable laser switches between specific current combinations, mode hopping easily occurs due to the lack of a correct correspondence between wavelength and current, resulting in unstable laser tuning.

[0005] To solve the above technical problems, the present invention provides a method for wavelength tuning of a tunable laser without mode hopping, comprising:

[0006] Scanning the reflection region current of the tunable laser based on a preset scanning strategy to obtain multiple step data;

[0007] Extracting valid step data from all step data, and dividing the valid step data belonging to the same wavelength tuning region into one group, to obtain multiple groups of valid data sets;

[0008] For each valid data set, the midpoints of all valid step data in the set are fitted to obtain the smooth wavelength tuning path corresponding to each valid data set;

[0009] Scan and verify each smooth wavelength tuning path and screen multiple feature points;

[0010] Perform positive and negative phase current loading at each characteristic point to obtain the phase region tuning curve corresponding to each characteristic point;

[0011] For each phase region tuning curve, the corresponding target wavelength is retrieved to obtain the maximum and minimum values ​​of the target wavelength;

[0012] In each smooth wavelength tuning path, the target wavelengths in all phase zone tuning curves are concatenated head to tail based on the maximum and minimum values ​​of the target wavelengths in ascending order of wavelength, to obtain the initial current tuning curve corresponding to each smooth wavelength tuning path;

[0013] For each initial current tuning curve, an interpolation method is used to generate intermediate wavelength data between the maximum and minimum values ​​of the target wavelength to obtain the corresponding target current tuning curve;

[0014] Based on all target current tuning curves, a current tuning curve in the full wavelength range is constructed as a wavelength-current lookup table to realize a mode-hopping-free wavelength tuning method for a tunable laser.

[0015] Preferably, scanning the reflection region current of the tunable laser based on a preset scanning strategy includes:

[0016] The preset scanning strategy includes a preset arc trajectory, a preset starting current, a preset ending current, a preset scanning step length and a preset scanning speed;

[0017] Based on a preset scanning strategy, the current in the left reflection area and the current in the right reflection area of ​​the tunable laser are scanned along a preset arc track.

[0018] Preferably, extracting valid step data from all step data includes:

[0019] Using a data processing algorithm to eliminate all invalid data in the step data, and treating the remaining step data as valid step data; the invalid data includes step data whose preceding and following data do not form an increasing or decreasing pattern;

[0020] For a plurality of valid step data with the same step height, valid step data with a larger width is obtained as the valid step data corresponding to the step.

[0021] Preferably, the scanning verification is performed on each wavelength tuning path to screen multiple characteristic points, including:

[0022] Based on the wavelength change rate of the wavelength tuning path, the wavelength tuning path is divided according to a preset current scale, and the divided points are obtained as feature points.

[0023] Preferably, performing positive and negative phase current loading at each characteristic point to obtain a phase region tuning curve corresponding to each characteristic point includes:

[0024] For each characteristic point in each wavelength tuning path, a coarse scanning method is used to load the phase zone current increment as positive to obtain the forward wavelength path corresponding to the characteristic point;

[0025] For each characteristic point in each wavelength tuning path, a coarse scanning method is used to load the phase zone current increment as a negative value to obtain the negative wavelength path corresponding to the characteristic point;

[0026] Based on the positive wavelength path and the negative wavelength path corresponding to each characteristic point, a phase region tuning curve corresponding to each characteristic point is obtained.

[0027] Preferably, for each phase region tuning curve, retrieving the corresponding target wavelength includes:

[0028] The phase region tuning curve includes a wavelength jump region and a coincidence tuning section;

[0029] In the overlapping tuning segments of each phase zone tuning curve, a linear segment with a wavelength change rate less than a preset change rate is retrieved, and the maximum and minimum wavelength values ​​therein are obtained as the target wavelength.

[0030] Preferably, in each smooth wavelength tuning path, the target wavelengths in all phase zone tuning curves are spliced ​​end to end based on the maximum and minimum values ​​of the target wavelengths in the order from small to large wavelengths to obtain the initial current tuning curve corresponding to each smooth wavelength tuning path, including:

[0031] Sort the target wavelengths in all phase region tuning curves in the smooth wavelength tuning path in ascending order of wavelength;

[0032] The maximum value of the i-th target wavelength and the minimum value of the i+1-th target wavelength are spliced ​​together until the target wavelengths in all phase zone tuning curves of the smooth wavelength tuning path are spliced ​​together to obtain the initial current tuning curve corresponding to the smooth wavelength tuning path.

[0033] Preferably, for each initial current tuning curve, generating intermediate wavelength data between the maximum value and the minimum value of the target wavelength by interpolation to obtain the corresponding target current tuning curve includes:

[0034] Preset maximum tuning range and minimum tuning step;

[0035] An arithmetic progression with a minimum tuning step as a tolerance is used, and the minimum and maximum values ​​of the target wavelength are used as the first and last elements in the arithmetic progression to fill the initial current tuning curve and obtain the corresponding target current tuning curve.

[0036] This embodiment provides a mode-hopping-free wavelength tuning device for a tunable laser, comprising:

[0037] The effective data acquisition module is used to scan the reflection area current of the tunable laser based on a preset scanning strategy to obtain multiple step data; extract the effective step data from all the step data, and divide the effective step data belonging to the same wavelength tuning area into one group to obtain multiple groups of effective data sets;

[0038] A smoothing module is used to fit the midpoints of all valid step data in each valid data set to obtain a smoothed wavelength tuning path corresponding to each valid data set;

[0039] The phase region tuning curve acquisition module is used to scan and verify each smooth wavelength tuning path and screen multiple characteristic points; the phase current is loaded forward and reverse at each characteristic point to obtain the phase region tuning curve corresponding to each characteristic point;

[0040] The initial current tuning curve acquisition module is used to retrieve the corresponding target wavelength for each phase zone tuning curve and obtain the maximum and minimum values ​​of the target wavelength. In each smooth wavelength tuning path, the target wavelengths in all phase zone tuning curves are spliced ​​end to end based on the maximum and minimum values ​​of the target wavelengths in ascending order of wavelength to obtain the initial current tuning curve corresponding to each smooth wavelength tuning path.

[0041] A target current tuning curve acquisition module is used to generate intermediate wavelength data between the maximum and minimum values ​​of the target wavelength for each initial current tuning curve using an interpolation method to acquire the corresponding target current tuning curve;

[0042] The tuning module is used to construct a current tuning curve in the full wavelength range based on all target current tuning curves as a wavelength current lookup table to implement a mode-hopping-free wavelength tuning method for a tunable laser.

[0043] This embodiment provides a mode-hopping-free wavelength tuning device for a tunable laser, including:

[0044] Temperature test chamber;

[0045] A laser module is placed in the temperature test chamber and is used to emit laser light;

[0046] Wavemeter, used to measure laser wavelength;

[0047] The mode-hopping wavelength tuning device of the tunable laser is communicatively connected with the laser module and the wavelength meter, and performs the steps of the mode-hopping wavelength tuning method of the tunable laser as described above.

[0048] The above technical solution of the present invention has the following beneficial effects compared with the prior art:

[0049] The method for mode-hopping wavelength tuning of a tunable laser described in the present invention scans the current in the reflection region of the tunable laser, extracts valid data, performs fitting, and obtains a corresponding smooth wavelength tuning path. Multiple characteristic points are selected on the smooth wavelength tuning path, and phase-region current is positively and negatively loaded at each characteristic point to construct a phase-region tuning curve. Positive and negative loading can fully observe the inconsistency of the phase-region current tuning curve, identify nonlinear or unstable behavior that the laser may exhibit during current switching, improve the accuracy of the wavelength current lookup table, and thus improve tuning stability. Furthermore, the method retrieves the target wavelength from each phase-region tuning curve, splices the curves based on the maximum and minimum values ​​of the target wavelength, and interpolates to obtain the target current tuning curve. The selection of the target wavelength in the present invention avoids most factors that cause wavelength hopping, ensuring that laser tuning does not produce mode hopping. Based on all target current tuning curves, a current tuning curve for the entire wavelength range is constructed to obtain a current data model that stably characterizes the wavelength, thereby achieving mode-hopping wavelength tuning of the tunable laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein

[0051] Figure 1 This is a flowchart of the steps of the mode-hopping-free wavelength tuning method of the tunable laser provided by the present invention;

[0052] Figure 2 is the output wavelength of the MG-Y laser and the current in the left reflection zone I LR , right reflex zone current I RR Mapping relationship diagram;

[0053] Figure 3 It is a general flow chart of the method for wavelength tuning of tunable laser without mode hopping;

[0054] Figure 4 is a diagram of the steps for obtaining the smooth wavelength tuning path;

[0055] Figure 5 is a strategy map for locating smooth wavelength tuning paths;

[0056] Figure 6 It is the smooth tuning path diagram of the tunable laser in the reflection area;

[0057] Figure 7 This is the flow chart for constructing the wavelength current meter;

[0058] Figure 8 It is a schematic diagram of feature points;

[0059] Figure 9 It is a schematic diagram of the phase region tuning curve;

[0060] Figure 10 is a schematic diagram of the initial current tuning curve;

[0061] Figure 11 is a schematic diagram of the target current tuning curve;

[0062] Figure 12 It is a schematic diagram of the current tuning curve in the full wavelength range;

[0063] Figure 13 It is a structural diagram of a mode-hopping-free wavelength tuning device for a tunable laser. DETAILED DESCRIPTION

[0064] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0065] Reference Figure 1 As shown in FIG, a flow chart of the method for mode-hopping wavelength tuning of a tunable laser of the present invention includes the following steps:

[0066] S101: Scanning the reflection region current of the tunable laser based on a preset scanning strategy to obtain a plurality of step data;

[0067] The preset scanning strategy includes a preset arc trajectory, a preset starting current, a preset ending current, a preset scanning step length and a preset scanning speed; based on the preset scanning strategy, the left reflection area current and the right reflection area current of the tunable laser are scanned along the preset arc trajectory.

[0068] S102: extracting valid step data from all step data, and dividing the valid step data belonging to the same wavelength tuning region into one group, to obtain multiple groups of valid data sets;

[0069] A data processing algorithm is used to eliminate all invalid data in the step data, and the remaining step data is used as valid step data; the invalid data includes step data whose previous and subsequent data do not form an increasing or decreasing pattern; for multiple valid step data with the same step height, valid step data with a larger width is obtained as the valid step data corresponding to the step.

[0070] S103: For each valid data set, fitting the midpoints of all valid step data in the set to obtain a smooth wavelength tuning path corresponding to each valid data set;

[0071] S104: Scan and verify each smooth wavelength tuning path, and select multiple feature points, including:

[0072] Based on the wavelength change rate of the wavelength tuning path, the wavelength tuning path is divided according to the preset current scale, and the divided points are obtained as feature points

[0073] S105: Performing positive and negative phase current loading at each characteristic point to obtain a phase region tuning curve corresponding to each characteristic point, including:

[0074] For each characteristic point in each wavelength tuning path, a coarse scanning method is used to load the phase zone current increment as positive to obtain the forward wavelength path corresponding to the characteristic point;

[0075] For each characteristic point in each wavelength tuning path, a coarse scanning method is used to load the phase zone current increment as a negative value to obtain the negative wavelength path corresponding to the characteristic point;

[0076] Based on the positive wavelength path and the negative wavelength path corresponding to each characteristic point, a phase region tuning curve corresponding to each characteristic point is obtained.

[0077] S106: For each phase region tuning curve, search for the corresponding target wavelength and obtain the maximum and minimum values ​​of the target wavelength;

[0078] The phase zone tuning curve includes a wavelength jump zone and an overlap tuning segment. In the overlap tuning segment of each phase zone tuning curve, a linear segment with a wavelength change rate less than a preset change rate is retrieved, and the maximum and minimum wavelength values ​​therein are obtained as the target wavelength.

[0079] S107: In each smooth wavelength tuning path, in ascending order of wavelength, the target wavelengths in all phase zone tuning curves are concatenated end to end based on the maximum and minimum values ​​of the target wavelengths to obtain an initial current tuning curve corresponding to each smooth wavelength tuning path;

[0080] The target wavelengths in all phase zone tuning curves in the smooth wavelength tuning path are sorted in ascending order; the maximum value of the i-th target wavelength and the minimum value of the i+1-th target wavelength are spliced ​​together until the target wavelengths in all phase zone tuning curves in the smooth wavelength tuning path are spliced ​​together to obtain the initial current tuning curve corresponding to the smooth wavelength tuning path.

[0081] S108: For each initial current tuning curve, generate intermediate wavelength data between the maximum and minimum values ​​of the target wavelength using an interpolation method to obtain a corresponding target current tuning curve;

[0082] The interpolation method of this embodiment presets the maximum tuning range and the minimum tuning step; uses an arithmetic progression with the minimum tuning step as the tolerance, and uses the minimum and maximum values ​​of the target wavelength as the first and last elements in the arithmetic progression to fill the initial current tuning curve and obtain the corresponding target current tuning curve.

[0083] S109: Based on all target current tuning curves, construct a current tuning curve in the full wavelength range as a wavelength current lookup table to implement a mode-hopping-free wavelength tuning method for a tunable laser.

[0084] The embodiment of the present invention improves the wavelength stability of the current tuning in the reflection zone by strategically scanning the current in the reflection zone and then fitting the most stable wavelength tuning path; by retrieving the target wavelength of the overlapping tuning segment in the phase zone, the tuning operating point avoids the jump window area in the phase zone, effectively solving the problem of mode hopping; the fine wavelength data is limited to the middle area of ​​the linear segment with relatively gentle changes, away from the boundary of the linear segment, and the current fluctuation has little effect on the wavelength, effectively improving the wavelength stability of the current tuning in the phase zone. The embodiment of the present invention is aimed at the wavelength tuning method without mode hopping of tunable lasers, inherits and develops the efficiency and universality of the existing technology, and through the left reflection zone current I LR , right reflection area current I RR , injection current I PH The combined characterization of all wavelength outputs of a tunable laser within its tuning range overcomes the defect of unstable tuning of lasers in the prior art and solves the problem of mode hopping when tuning the laser between specific operating points.

[0085] Based on the above embodiment, in an embodiment of the present invention, the process of the method for tuning the wavelength of a tunable laser without mode hopping includes:

[0086] S201: Scan the current in the reflection area according to the strategy to obtain step data;

[0087] Among them, the scanning strategy can fully reflect the supermode wavelength characteristics; the strategy has more test points in the narrow area of ​​the supermode; and the scanning current covers the adjustable range of the laser.

[0088] S202: Extracting the midpoint of the effective step data, fitting different sample points belonging to the same supermode, and restoring a smooth wavelength tuning path, including:

[0089] Eliminate invalid parts of step data through data processing algorithms;

[0090] If there are steps with the same height, the midpoint of the step with the larger width will be kept first;

[0091] The sample points belonging to the same supermodel are grouped together to obtain multiple groups of sampling points for multiple paths;

[0092] Each group of sample points is fitted using piecewise linear fitting method;

[0093] The fitting function is used as an expression of the tuning path to characterize the most stable wavelength tuning path.

[0094] S203: performing positive and negative phase current loading on the characteristic points under each group of paths to obtain a coincident tuning curve;

[0095] The number of selected feature points decreases as the current in the reflection zone increases; the selected feature points are loaded in a manner where the current increment in the phase zone is positive or negative, the loading method is coarse scanning, and the loading range complies with the electrical specifications of the laser.

[0096] S204: Retrieve the maximum and minimum wavelength values ​​of the overlapping linear segments and perform end-to-end splicing;

[0097] This embodiment limits the search for target wavelengths in overlapping tuning segments; prioritizes the search for overlapping linear segments with lower tuning coefficients; searches for the maximum wavelength located in the middle area of ​​the linear segments; concatenates the maximum wavelength of one linear segment with the minimum wavelength of the next linear segment, and so on.

[0098] S205: Fill in the remaining fine wavelength data using a linear interpolation method to construct a wavelength current lookup table for the laser, including:

[0099] Specify the maximum tuning range and minimum tuning step;

[0100] The splicing results within the tuning range are filled with an arithmetic progression, and the tolerance is the minimum tuning step;

[0101] Get the specified wavelength and left reflection area current I LR , right reflex zone current I RR , injection current I PH The corresponding relationship of the combination.

[0102] The present invention inherits and develops the efficiency and universality of the prior art, and can be LR, I RR , I PH The combined characterization of all wavelength outputs of the MG-Y tunable laser within its tuning range overcomes the current defect of unstable tuning of the DBR laser, and particularly solves the problem of mode hopping when the laser switches between specific operating points. This relates to the field of optical fiber sensing, and in particular to the field of tunable semiconductor laser technology.

[0103] Specifically, in the embodiment of the present invention, the target wavelength is selected so as to avoid the target wavelength being in the jump zone due to the positive and negative loading effects of the phase zone, which leads to the existence of a jump zone and an overlapping tuning zone in the phase zone tuning segment. This effectively solves the problem of laser mode jump. By selecting a linear segment with a smoother wavelength change, the influence of current fluctuation on wavelength deviation is reduced. Since wavelength jumps are prone to occur in boundary data, a wavelength far away from the boundary of the linear segment is selected.

[0104] Based on the above embodiment, in the embodiment of the present invention, the wavelength of a typical MG-Y laser is tuned; Figure 2 As shown, the output wavelength of the MG-Y laser and the current I in the left reflection area LR , right reflex zone current I RR The mapping relationship diagram of the wavelength tuning area is shown in Figure 2; there are wavelength tuning areas of different colors on the plane, which are called supermodes, that is, wavelength tuning areas. For the data provided in this embodiment, there are 11 supermodes in total. The same supermode covers an average wavelength tuning range of 5nm, and the larger the current in the reflection area, the smaller the wavelength. There is a clear boundary line between adjacent supermodes. The wavelength stability in the boundary area is poor and mode hopping is prone to occur. Therefore, in order to improve the wavelength stability of the current tuning in the reflection area, it is necessary to ensure that I LR , I RR are all located in the center of the supermode. In practical applications, the current combination of the reflection area is usually found along the center line of the supermode to obtain a smooth wavelength tuning path. Obviously, through Figure 2 The mapping relationship shown can quickly find a smooth wavelength tuning path, but it must traverse and scan the currents in all reflection areas, which is inefficient.

[0105] like Figure 3 As shown, the summary flow chart of the mode-hopping wavelength tuning method of a tunable laser provided by an embodiment of the present invention is summarized into six steps, including: scanning the current in the reflection area according to the strategy; extracting the midpoint of the effective step data; fitting a smooth wavelength tuning path; positively and negatively loading the phase area current; retrieving the wavelength maximum; and interpolating the fine wavelength.

[0106] Specifically, such as Figure 4As shown in the figure, the steps for obtaining a smooth wavelength tuning path need to be obtained first, which involves six specific steps, including: scanning the currents in the left and right reflection areas along an arc trajectory; eliminating invalid data in the data set through a data processing algorithm; obtaining valid wavelength data with complete step changes; extracting the midpoint of the valid step data; restoring the smooth wavelength tuning path using a piecewise linear fitting method; and characterizing the most stable tuning path through a fitting function.

[0107] like Figure 5 As shown in FIG, a strategy diagram for locating a smooth wavelength tuning path; the arc track is denser in the narrow supermode area, and three arcs are set within 0mA to 5mA; the current range of the track is between 0mA and 30mA, covering the adjustable range of the laser; the track is arc-shaped, with less scanning volume, but it is a rectangular frame when the current in the reflection area is 30mA; when scanning the current in the reflection area according to the arc track, the fixed I PH The current is zero. Eliminate invalid data in the arc scanning results, mainly eliminating the invalid data at I RR or I LR The wavelength data at the larger point is obtained; the midpoint of the step is extracted from the obtained effective step data. If there are two heights of steps, the midpoint of the step with the larger width is retained first; the middle area of ​​the step has a higher SMSR; the larger the step width, the higher the wavelength stability.

[0108] The sample points belonging to the same supermode are grouped together to obtain multiple groups of sampling points for multiple paths. After performing piecewise linear fitting on each group of sample points, a smooth wavelength tuning path can be obtained, which is a piecewise linear function, such as Figure 6 As shown in FIG, a smooth tuning path diagram of a tunable laser in the reflection region.

[0109] like Figure 7 As shown, it is a flow chart for constructing a wavelength current table; after obtaining a smooth wavelength tuning path, it includes: extracting characteristic points in the path; loading the characteristic points in a manner of increasing and decreasing current in the phase zone; obtaining overlapping tuning segments; screening the middle area data of the linear segment with smoother wavelength variation; retrieving the maximum wavelength and minimum wavelength of the screened linear segment; splicing the wavelength extremes; performing wavelength interpolation between the wavelength extremes; constructing a wavelength current lookup table; and stably characterizing all wavelength outputs through current combinations.

[0110] Scan a path and get Figure 8 The wavelength is discontinuous, so it is difficult to achieve fine wavelength tuning by relying solely on the current in the reflection area. As the current in the reflection area increases, the wavelength change rate decreases, which means that when the current in the reflection area is large, the current combination of adjacent reflection areas is larger than the wavelength in the reflection area. PHThe fine-tuning has a highly overlapping tuning range, so the number of selected feature points should be appropriately reduced as the current in the reflection area increases.

[0111] The selected feature points are roughly scanned along the direction of increasing and decreasing current in the phase zone, with increments of +0.2mA and –0.2mA, and a scanning range of 0 to 7mA, which complies with the electrical specifications of the laser phase zone; the following is obtained: Figure 9 The phase region tuning curve diagram shown in the figure shows that there are wavelength jump regions and overlapping tuning segments. In each linear segment, as I PH Increases, the wavelength decreases, and vice versa; the current combination of each reflection area passes through I PH Fine-tuning provides a tuning range of approximately 0.3nm. To avoid tuning wavelengths in phase-jump regions, the target wavelength is searched for within the coincident tuning segment, where the wavelength is stable and effectively addresses the issue of laser mode hopping. Priority is given to searching within the coincident tuning segment with a lower tuning coefficient, where current fluctuations have a minimal effect on the wavelength, facilitating the retrieval of more stable wavelength data. Data located in the middle of the linear segment, away from the edge of the segment, is specifically searched to avoid segment jumps.

[0112] According to the filtered data, the maximum wavelength and minimum wavelength of each linear segment are retrieved and spliced. Taking a certain path as an example, the splicing method of the wavelength maximum value is explained. Figure 10 The figure shows the initial current tuning curve, which has a denser number of wavelength points and no Figure 8 Intermittent display issues.

[0113] In this embodiment, the laser tuning range is set to 40 nm, the minimum tuning step is 4 pm, and the wavelength interpolation is performed on the wavelength maximum, such as Figure 11 As shown, it is a schematic diagram of the target current tuning curve; the fine wavelength data is filled with an arithmetic progression.

[0114] Collect all fine wavelength data and construct a wavelength current lookup table with a tuning range of 1528nm to 1568nm and a resolution of 4pm, such as Figure 12 The figure shows the current tuning curve in the full wavelength range. PHFine-tuning can characterize all wavelength outputs within the laser's tuning range. The phase-zone current forward and reverse loading method provided in this example, unlike existing techniques that only load phase-zone current in one direction, allows for full observation of the inconsistencies in the phase-zone current tuning curve. The presence of the jump region is precisely why tunable lasers are prone to mode hopping when switching between specific current combinations. The target wavelength search method based on overlapping tuning segments provided in this example avoids most factors that cause wavelength hopping in the final wavelength search result. The remaining factors may manifest themselves in the positioning of smooth wavelength tuning paths, the screening of gently varying linear segments, and the extraction of data in the intermediate regions of the linear segments. Taking these considerations into account, the method provided in this example theoretically ensures that laser tuning will not produce mode hopping, and a stable current data model that characterizes the wavelength can be obtained.

[0115] Based on the above embodiments, an embodiment of the present invention provides a mode-hopping-free wavelength tuning device, including:

[0116] The effective data acquisition module 100 is used to scan the reflection region current of the tunable laser based on a preset scanning strategy to obtain multiple step data; extract the effective step data from all the step data, and divide the effective step data belonging to the same wavelength tuning region into one group to obtain multiple groups of effective data sets;

[0117] The smoothing module 200 is used to fit the midpoints of all valid step data in each valid data set to obtain a smoothed wavelength tuning path corresponding to each valid data set;

[0118] The phase region tuning curve acquisition module 300 is used to scan and verify each smooth wavelength tuning path and select multiple characteristic points; perform positive and negative phase current loading at each characteristic point to obtain the phase region tuning curve corresponding to each characteristic point;

[0119] The initial current tuning curve acquisition module 400 is configured to retrieve the corresponding target wavelength for each phase zone tuning curve and obtain the maximum and minimum values ​​of the target wavelength. In each smooth wavelength tuning path, the target wavelengths in all phase zone tuning curves are concatenated end to end based on the maximum and minimum values ​​of the target wavelengths in ascending order of wavelength to obtain the initial current tuning curve corresponding to each smooth wavelength tuning path.

[0120] The target current tuning curve acquisition module 500 is used to generate intermediate wavelength data between the maximum and minimum values ​​of the target wavelength for each initial current tuning curve using an interpolation method to acquire the corresponding target current tuning curve;

[0121] The tuning module 600 is used to construct a current tuning curve in the full wavelength range based on all target current tuning curves as a wavelength-current lookup table to implement a mode-hopping-free wavelength tuning method for a tunable laser.

[0122] The mode-hopping wavelength tuning device of the tunable laser of this embodiment is used to implement the mode-hopping wavelength tuning method of the tunable laser described above. Therefore, the specific implementation of the mode-hopping wavelength tuning device of the tunable laser can be seen in the embodiment of the mode-hopping wavelength tuning method of the tunable laser described above. For example, the effective data acquisition module 100 is used to implement steps S101 and S102 in the mode-hopping wavelength tuning method of the tunable laser described above; the smoothing module 200 is used to implement step S103 in the mode-hopping wavelength tuning method of the tunable laser described above; the phase zone tuning curve acquisition module 3 00, used to implement steps S104 and S105 in the above-mentioned mode-hopping wavelength tuning method for the tunable laser; an initial current tuning curve acquisition module 400, used to implement steps S106 and S107 in the above-mentioned mode-hopping wavelength tuning method for the tunable laser; a target current tuning curve acquisition module 500, used to implement step S108 in the above-mentioned mode-hopping wavelength tuning method for the tunable laser; a tuning module 600, used to implement step S109 in the above-mentioned mode-hopping wavelength tuning method for the tunable laser; its specific implementation methods can refer to the description of the corresponding various parts of the embodiments, which will not be repeated here.

[0123] Based on the above embodiment, an embodiment of the present invention further provides a mode-hopping-free wavelength tuning device for a tunable laser, comprising:

[0124] Temperature test chamber;

[0125] A laser module is placed in the temperature test chamber and is used to emit laser light;

[0126] Wavemeter, used to measure laser wavelength;

[0127] The mode-hopping wavelength tuning device of the tunable laser is communicatively connected with the laser module and the wavelength meter, and performs the steps of the mode-hopping wavelength tuning method of the tunable laser as described above.

[0128] Reference Figure 13 Figure 2 shows the structure of a mode-hopping-free wavelength tuning device for a tunable laser. It includes a wavelength meter, a laser module, a temperature test chamber, and a PC. The laser module is located within the temperature test chamber to prevent environmental interference with laser tuning. The PC communicates with both the laser module and the wavelength meter to ensure synchronized acquisition of laser output.

[0129] In this embodiment, the wavelength meter detection range covers the tuning range of the laser, and the accuracy reaches 0.2pm, which is capable of completing the work of laser wavelength calibration and provides multiple remote control interfaces, including Ethernet, GPI B, etc.

[0130] In this embodiment, the laser module consists of a laser and its driving circuit. The laser is controlled by five current channels, so there are five constant current sources to provide variable current injection. The integrated temperature chip ensures the stability of the internal temperature of the laser, so that the laser can be stably tuned. A serial communication interface is provided so that the control of the laser can be executed on the host PC.

[0131] In this embodiment, the external environment is an important factor affecting the wavelength tuning of the tunable laser. Therefore, during the entire implementation process of the example, the laser module is placed in a temperature test chamber, and the temperature test chamber is used to control the experimental environment to maintain stability.

[0132] In this embodiment, the PC, namely the mode-hopping wavelength tuning device for a tunable laser provided by the embodiment of the present invention, is used to control the wavelength meter and the laser module, and provides a friendly control interface.

[0133] The laser module and wavelength meter are connected to a PC via RS232 and TCP / IP protocols to ensure synchronous acquisition of the laser output. The wavelength and corresponding current combination are recorded in the PC, facilitating the execution of the tunable laser mode-hopping wavelength tuning method described in the examples of the present invention.

[0134] The device of the present invention needs to be preheated before use, including preheating the laser for 30 minutes; preheating the temperature test box until the internal temperature measured by the thermocouple remains stable for 30 minutes.

[0135] The method, device, and apparatus for mode-hopping wavelength tuning of a tunable laser disclosed herein scan the current in the reflection region of the tunable laser, extract valid data, perform fitting, and obtain a corresponding smooth wavelength tuning path. Multiple characteristic points are selected on the smooth wavelength tuning path, and phase-region current is positively and negatively loaded at each characteristic point to construct a phase-region tuning curve. Positive and negative loading can fully observe inconsistencies in the phase-region current tuning curve, identify nonlinear or unstable behavior that the laser may exhibit during current switching, improve the accuracy of constructing the wavelength current lookup table, and thereby improve tuning stability. Furthermore, the present invention retrieves a target wavelength from each phase-region tuning curve, splices the curves based on the maximum and minimum values ​​of the target wavelength, and interpolates to obtain the target current tuning curve. The selection of the target wavelength in the present invention avoids most factors that cause wavelength hopping, ensuring that laser tuning does not produce mode hopping. Based on all target current tuning curves, a current tuning curve for the entire wavelength range is constructed to obtain a current data model that stably characterizes the wavelength, thereby achieving mode-hopping wavelength tuning of the tunable laser.

[0136] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0137] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0138] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1The function specified in one or more boxes.

[0139] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0140] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for tuning wavelength of a tunable laser without mode hopping, characterized in that: include: Scanning the reflection region current of the tunable laser based on a preset scanning strategy to obtain multiple step data; Extracting valid step data from all step data, and dividing the valid step data belonging to the same wavelength tuning region into one group, to obtain multiple groups of valid data sets; For each valid data set, the midpoints of all valid step data in the set are fitted to obtain the smooth wavelength tuning path corresponding to each valid data set; Scan and verify each smooth wavelength tuning path and screen multiple feature points; Perform positive and negative phase current loading at each characteristic point to obtain the phase region tuning curve corresponding to each characteristic point; For each phase region tuning curve, the corresponding target wavelength is retrieved to obtain the maximum and minimum values ​​of the target wavelength; In each smooth wavelength tuning path, the target wavelengths in all phase zone tuning curves are concatenated head to tail based on the maximum and minimum values ​​of the target wavelengths in ascending order of wavelength, to obtain the initial current tuning curve corresponding to each smooth wavelength tuning path; For each initial current tuning curve, an interpolation method is used to generate intermediate wavelength data between the maximum and minimum values ​​of the target wavelength to obtain the corresponding target current tuning curve; Based on all target current tuning curves, a current tuning curve in the full wavelength range is constructed as a wavelength-current lookup table to realize a mode-hopping-free wavelength tuning method for a tunable laser.

2. The method for mode-hopping wavelength tuning of a tunable laser according to claim 1, wherein: The scanning of the reflection region current of the tunable laser based on a preset scanning strategy includes: The preset scanning strategy includes a preset arc trajectory, a preset starting current, a preset ending current, a preset scanning step length and a preset scanning speed; Based on a preset scanning strategy, the current in the left reflection area and the current in the right reflection area of ​​the tunable laser are scanned along a preset arc track.

3. The method for wavelength tuning of a tunable laser without mode hopping according to claim 1, wherein: The step of extracting valid ladder data from all ladder data includes: Using a data processing algorithm to eliminate all invalid data in the step data, and treating the remaining step data as valid step data; the invalid data includes step data whose preceding and following data do not form an increasing or decreasing pattern; For a plurality of valid step data with the same step height, valid step data with a larger width is obtained as the valid step data corresponding to the step.

4. The method for tuning wavelength of a tunable laser without mode hopping according to claim 1, wherein: Each smooth wavelength tuning path is scanned and verified to screen multiple feature points, including: Based on the wavelength change rate of the wavelength tuning path, the wavelength tuning path is divided according to a preset current scale, and the divided points are obtained as feature points.

5. The method for mode-hopping wavelength tuning of a tunable laser according to claim 1, wherein: The phase current is loaded forward and reversely at each characteristic point to obtain a phase region tuning curve corresponding to each characteristic point, including: For each characteristic point in each wavelength tuning path, a coarse scanning method is used to load the phase zone current increment as positive to obtain the forward wavelength path corresponding to the characteristic point; For each characteristic point in each wavelength tuning path, a coarse scanning method is used to load the phase zone current increment as a negative value to obtain the negative wavelength path corresponding to the characteristic point; Based on the positive wavelength path and the negative wavelength path corresponding to each characteristic point, a phase region tuning curve corresponding to each characteristic point is obtained.

6. The method for mode-hopping wavelength tuning of a tunable laser according to claim 1, wherein: The step of retrieving the corresponding target wavelength for each phase region tuning curve comprises: The phase region tuning curve includes a wavelength jump region and a coincidence tuning section; In the overlapping tuning segments of each phase zone tuning curve, a linear segment with a wavelength change rate less than a preset change rate is retrieved, and the maximum and minimum wavelength values ​​therein are obtained as the target wavelength.

7. The method for mode-hopping wavelength tuning of a tunable laser according to claim 1, wherein: In each smooth wavelength tuning path, the target wavelengths in all phase zone tuning curves are spliced ​​end to end based on the maximum and minimum values ​​of the target wavelengths in order from small to large wavelengths to obtain the initial current tuning curve corresponding to each smooth wavelength tuning path, including: Sort the target wavelengths in all phase region tuning curves in the smooth wavelength tuning path in ascending order of wavelength; The maximum value of the i-th target wavelength and the minimum value of the i+1-th target wavelength are spliced ​​together until the target wavelengths in all phase zone tuning curves of the smooth wavelength tuning path are spliced ​​together to obtain the initial current tuning curve corresponding to the smooth wavelength tuning path.

8. The method for mode-hopping wavelength tuning of a tunable laser according to claim 1, wherein: For each initial current tuning curve, using an interpolation method to generate intermediate wavelength data between the maximum value and the minimum value of the target wavelength to obtain the corresponding target current tuning curve includes: Preset maximum tuning range and minimum tuning step; An arithmetic progression with a minimum tuning step as a tolerance is used, and the minimum and maximum values ​​of the target wavelength are used as the first and last elements in the arithmetic progression to fill the initial current tuning curve and obtain the corresponding target current tuning curve.

9. A mode-hopping wavelength tuning device for a tunable laser, characterized in that: include: An effective data acquisition module is used to scan the reflection area current of the tunable laser based on a preset scanning strategy to obtain multiple step data; Extracting valid step data from all step data, and dividing the valid step data belonging to the same wavelength tuning region into one group, to obtain multiple groups of valid data sets; A smoothing module is used to fit the midpoints of all valid step data in each valid data set to obtain a smoothed wavelength tuning path corresponding to each valid data set; The phase region tuning curve acquisition module is used to scan and verify each smooth wavelength tuning path and screen multiple characteristic points; the phase current is loaded forward and reverse at each characteristic point to obtain the phase region tuning curve corresponding to each characteristic point; An initial current tuning curve acquisition module is used to retrieve the corresponding target wavelength for each phase zone tuning curve and obtain the maximum and minimum values ​​of the target wavelength; In each smooth wavelength tuning path, the target wavelengths in all phase zone tuning curves are concatenated head to tail based on the maximum and minimum values ​​of the target wavelengths in ascending order of wavelength, to obtain the initial current tuning curve corresponding to each smooth wavelength tuning path; A target current tuning curve acquisition module is used to generate intermediate wavelength data between the maximum and minimum values ​​of the target wavelength for each initial current tuning curve using an interpolation method to acquire the corresponding target current tuning curve; The tuning module is used to construct a current tuning curve in the full wavelength range based on all target current tuning curves as a wavelength current lookup table to implement a mode-hopping-free wavelength tuning method for a tunable laser.

10. A mode-hopping wavelength tuning device for a tunable laser, characterized in that: include: Temperature test chamber; A laser module is placed in the temperature test chamber and is used to emit laser light; Wavemeter, used to measure laser wavelength; The mode-hopping wavelength tuning device of the tunable laser is communicatively connected with the laser module and the wavelength meter, and performs the steps of the mode-hopping wavelength tuning method of the tunable laser according to any one of claims 1 to 8.

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