CN-121978833-A - Method for determining working distance of slow axis collimating lens in optical fiber coupling module

CN121978833ACN 121978833 ACN121978833 ACN 121978833ACN-121978833-A

Abstract

The invention relates to the field of optical fiber coupling modules, in particular to a method for determining the working distance of a slow-axis collimating lens in an optical fiber coupling module, which is characterized by acquiring the temperature distribution range of a pumping chip and the slow-axis collimating lens in an actual working state through thermal simulation or actual measurement, testing the performance parameters of the pumping chip along with the temperature change in the temperature range, constructing a thermal-optical coupling simulation model, configuring the temperature distribution and the performance parameters in the model, setting a gradient temperature field, simulating the changing relation of the coupling efficiency of a system along with the working distance between the lens and the chip to obtain a plurality of groups of simulation data, taking the efficiency stability of a full-temperature area as constraint, taking the maximization of average efficiency as a target, and determining a globally optimal fixed working distance through optimization calculation. The invention avoids the problems of safety risk and efficiency of traditional power-up regulation, compensates the optical performance drift caused by the change of the working temperature, thereby realizing the improvement of coupling efficiency, precision and stability in a full-temperature area and improving the qualification rate of mass production.

Inventors

JU ZHIYUAN
KONG LINGCHANG
YANG JUNSHUAI
LIU QI
QIN HUABING
WU DEHUA

Assignees

山东华光光电子股份有限公司

Dates

Publication Date: 20260505
Application Date: 20260115

Claims (10)

1. The method for determining the working distance of the slow axis collimating lens in the optical fiber coupling module is characterized by comprising the following steps of: s1, obtaining a first working temperature range of a pumping chip position and a second working temperature range of a slow axis collimating lens position of a pumping source module of the fiber laser in an actual working state through thermal simulation or actual test; S2, selecting a plurality of temperature points in a first working temperature range, controlling the working temperature of the pump chip to each set temperature point through a temperature control platform, and measuring the working performance parameters of the pump chip at each temperature point; S3, constructing an optical coupling simulation model comprising a slow axis collimating lens and a pumping chip, configuring a temperature parameter corresponding to a first working temperature range and the working performance parameter for the pumping chip in the simulation model, configuring a lens material temperature attribute corresponding to the first working temperature range for the slow axis collimating lens, setting a non-uniform gradient temperature field, simulating the changing relation of the coupling efficiency of the optical fiber coupling module along with the working distance between the slow axis collimating lens and the pumping chip in the first working temperature range and the second working temperature range, and obtaining a plurality of groups of simulation data; s4, based on multiple groups of simulation data, taking the requirement of meeting preset stability as a constraint condition, taking the maximum full-temperature area average coupling efficiency as a target, and determining the optimal fixed working distance between the slow axis collimating lens and the pumping chip through optimization calculation.
2. The method for determining the working distance of a slow axis collimating lens in an optical fiber coupling module according to claim 1, wherein the process of obtaining the temperature range in step S1 by thermal simulation specifically comprises: Constructing a three-dimensional thermal simulation model of a pumping source module of the fiber laser, wherein the model at least comprises a pumping chip serving as a heat source, a slow axis collimating lens, a thermal interface material and a radiator; In the three-dimensional thermal simulation model, setting heating power corresponding to the rated working state of the pump chip, and setting environmental temperature and surface convection heat exchange boundary conditions; dividing grids of the three-dimensional thermal simulation model, and encrypting grids in the areas where the pump chip and the slow axis collimating lens are located; and performing transient thermal simulation analysis, wherein the simulation duration covers the whole process from starting to reaching thermal balance of the pumping source module of the fiber laser, and the first working temperature range of the pumping chip position and the second working temperature range of the slow axis collimating lens position under steady state or quasi-steady state are obtained.
3. The method for determining the working distance of a slow axis collimating lens in an optical fiber coupling module according to claim 1, wherein the step S1 of obtaining the temperature range through an actual test specifically comprises: temperature sensors are respectively distributed on the surface of the pumping chip and the mounting base of the slow axis collimating lens; Placing the pumping source module of the fiber laser in a temperature control environment box, and electrifying the pumping source module to operate under the rated working condition; Temperature data for at least 3 complete operating cycles are recorded in succession, and a first operating temperature range and a second operating temperature range are extracted from the recorded data and determined.
4. The method of claim 1, wherein the operating performance parameters of the pump chip measured in step S2 include at least wavelength and slow axis divergence angle.
5. The method for determining the working distance of a slow axis collimating lens in an optical fiber coupling module according to claim 4, wherein step S2 specifically comprises: the method comprises the steps that a pump chip is arranged on a high-precision temperature control platform, and a spectrometer and a beam analyzer are sequentially arranged in the light path output direction of the pump chip; Sequentially setting at least three discrete target temperature points in a first working temperature range, and sequentially controlling the working temperature of the pump chip at each target temperature point through a temperature control platform; When the working temperature of the pumping chip is at each target temperature point, driving the pumping chip to emit light under constant current, synchronously measuring the central wavelength of the output laser by using a spectrometer, and measuring the divergence angle of the slow axis direction by using a beam analyzer; And recording the measured value of each target temperature point, the corresponding central wavelength and the slow axis divergence angle to form a working performance parameter data set of the pump chip.
6. The method according to claim 1, wherein the optical coupling simulation model in step S3 is constructed in a non-sequential ray trace mode in optical design software.
7. The method for determining the working distance of a slow axis collimating lens in an optical fiber coupling module according to claim 6, wherein the configuration of the temperature parameter corresponding to the first working temperature range and the working performance parameter for the pump chip specifically comprises: Based on the working performance parameters obtained in the step S2, a mapping table or fitting function of the corresponding relation between the working temperature of the pump chip and the input wavelength and the slow axis divergence angle of the pump chip is established; setting a specific temperature value selected from a first working temperature range for the pumping chip element in the light source attribute of the simulation model to define a thermal state of the pumping chip element; according to the established mapping relation, the wavelength measurement value corresponding to the temperature value is configured as the emission wavelength of the light source, and the slow axis divergence angle measurement value corresponding to the temperature value is configured as the slow axis direction divergence angle of the light source.
8. The method of claim 6, wherein the lens material temperature properties of the slow axis collimator lens include at least a thermal expansion coefficient and a refractive index temperature coefficient.
9. The method for determining the working distance of a slow axis collimating lens in an optical fiber coupling module according to claim 6, wherein the method comprises simulating a relationship of coupling efficiency of the optical fiber coupling module with a working distance between the slow axis collimating lens and a pump chip in a first and a second working temperature ranges to obtain a plurality of groups of simulation data, and the method specifically comprises: a) Setting the position of the slow axis collimating lens in the optical axis direction as a variable, and defining a scanning range and a scanning step length for the slow axis collimating lens; b) For each position value in the scanning range, executing ray tracing under a gradient temperature field, and calculating the coupling efficiency of the light emitted by the pump chip, which is coupled to the target optical fiber after passing through the slow axis collimating lens; c) Recording each position value and the corresponding coupling efficiency value thereof to form a group of simulation data representing the change of the coupling efficiency along with the working distance under a specific temperature field; d) And iteratively executing the steps a) to c) by changing the assignment of the first temperature point and the second temperature point to obtain a plurality of groups of simulation data corresponding to different working temperature states.
10. The method for determining the working distance of a slow axis collimating lens in an optical fiber coupling module according to claim 1, wherein step S4 specifically comprises: Constructing an objective function and a constraint function taking a working distance as a variable based on a plurality of groups of simulation data, wherein the objective function represents the average coupling efficiency of the optical fiber coupling model in a first working temperature range and a second working temperature range; executing a numerical optimization algorithm in a mechanically feasible interval of the working distance, and searching a solution for enabling the objective function to be maximum under the condition that the constraint function meets the preset stability requirement; the solution is determined as the optimal fixed working distance between the slow axis collimating lens and the pump chip.

Description

Method for determining working distance of slow axis collimating lens in optical fiber coupling module Technical Field The invention relates to the field of optical fiber coupling modules, in particular to a method for determining the working distance of a slow axis collimating lens in an optical fiber coupling module. Background In the manufacturing process of the optical fiber coupling module, the coupling of optical components is a key link, and the optical transmission efficiency, the output power stability and the service life of the pump source module are directly influenced. The precise coupling of components such as a slow axis collimating lens, a coupling lens, a FAC (Fast Axis Collimator) lens, a VBG (Volume Bragg Grating ) and the like, a pumping chip and a passive optical fiber is the core for improving the coupling efficiency. The traditional optical fiber coupling module coupling process mostly adopts a power-on adjustment mode, namely, a pumping chip is powered on to emit light, and then the positions of optical components such as a slow axis collimating lens and the like are manually or semi-automatically adjusted, so that the optimization of coupling efficiency is realized. However, the method has the defects that on one hand, high-power laser emitted by the pump chip in the power-up process has serious safety risks, threatens personal safety of operators and equipment safety, on the other hand, working environments (such as temperature, humidity and the like) in power-up adjustment often have differences with actual working environments of the pump source module, so that the adjusted coupling state deviates from the actual application, performance of the pump source is affected, in addition, the power-up adjustment process is complicated, repeated start-up and stop and debugging are needed, the working and adjustment efficiency is low, the mass production efficiency of the optical fiber coupling module is seriously restricted, and the risk of failure of the laser chip is increased due to repeated start-up and stop. In addition, experiments prove that the traditional power-on adjustment process is caused by thermally-induced wavelength drift (0.03 nm/DEG C) and lens refractive index change (delta n=1.2×10 -5/DEG C) under the working environment. However, the effect of temperature variations on the performance of optical components is generally ignored in the related art. When the optical fiber coupling module works, a large amount of heat is generated, so that the working temperatures of the pump chip and the optical components are obviously changed, and the temperature change can cause a series of three-order coupling failure problems of 1) wavelength drift (typical value of 0.03 nm/DEG C) of the pump chip, further VBG wavelength mismatch, 2) refractive index change (delta n=1.2×10 -5/DEG C) of the lens, working distance deviation of +/-3 mu m/10℃, and 3) slow axis divergence angle change (0.02 DEG/DEG C) of the chip, and light spot distortion is caused. The problems cause the problems of coupling efficiency reduction, unstable output power and the like of the optical fiber coupling module in actual work due to temperature fluctuation, and the mass production qualification rate of the traditional process is lower, which is only about 80 percent. Therefore, a method capable of avoiding the conventional power-up adjustment defect, considering the temperature influence and improving the coupling efficiency is needed. Disclosure of Invention In order to solve the problems, the invention provides a method for determining the working distance of a slow axis collimating lens in an optical fiber coupling module for improving the coupling efficiency, which avoids the problems of safety risk and efficiency of traditional power-on adjustment through thermal-optical parameter coupling simulation, compensates the optical performance drift caused by the change of the working temperature, thereby improving the coupling efficiency, the accuracy and the stability in a full temperature area and improving the mass production qualification rate. The technical scheme of the invention provides a method for determining the working distance of a slow axis collimating lens in an optical fiber coupling module, which comprises the following steps: s1, obtaining a first working temperature range of a pumping chip position and a second working temperature range of a slow axis collimating lens position of a pumping source module of the fiber laser in an actual working state through thermal simulation or actual test; S2, selecting a plurality of temperature points in a first working temperature range, controlling the working temperature of the pump chip to each set temperature point through a temperature control platform, and measuring the working performance parameters of the pump chip at each temperature point; S3, constructing an optical coupling simulation model comprising a slow axis collimating lens and a pumping