Wavelength selection method and wavelength selection device for tunable laser

Patent metadata

Field	Value
Publication number	US-11817671-B2
Application number	US-202217807552-A
Country	US
Kind code	B2
Filing date	Jun 17, 2022
Priority date	Sep 10, 2018
Publication date	Nov 14, 2023
Grant date	Nov 14, 2023

Abstract

A wavelength selection method for a tunable laser includes: obtaining a target wavelength; and calculating target resistance values of two thermistors, respectively, corresponding to the target wavelength. Each of the two thermistors is used to monitor the temperature of a corresponding one of two wavelength selection components. Each of the target resistance values is calculated according to a relationship between a wavelength drift and a resistance change of the corresponding thermistor and according to an initial wavelength and an initial resistance value of the corresponding thermistor corresponding to the initial wavelength. The method further includes: heating the two wavelength selection components to control their temperatures until real-time resistance values of the two thermistors reach the target resistance values, respectively; and stabilizing the real-time resistance values at the target resistance values and outputting a laser beam having the target wavelength.

First claim

What is claimed is:

1. A wavelength selection method for a tunable laser, providing a Vernier system that comprises at least two thermally tunable wavelength selection components, wherein the at least two thermally tunable wavelength selection components include a first thermally tunable wavelength selection component and a second thermally tunable wavelength selection component, each of the wavelength selection components is configured with a heating component for heating the wavelength selection component, and a thermistor for monitoring the temperature of the wavelength selection component;
the wavelength selection method comprising:
obtaining a target wavelength λ;
obtaining target resistance values R 1 and R 2 of the two thermistors, respectively configured with the first and second wavelength selection components, respectively corresponding to the target wavelength λ;
heating the heating components configured with the first and second wavelength selection components to control the temperatures of the first and second wavelength selection components until real-time resistance values of the two thermistors reach the target resistance values R 1 and R 2 , respectively; and
stabilizing the real-time resistance values of the two thermistors at the target resistance values R 1 and R 2 , respectively, and outputting a laser beam having the target wavelength λ,

wherein the obtaining the target resistance values R 1 and R 2 of the two thermistors comprises: calculating the target resistance values R 1 and R 2 of the two thermistors, respectively, corresponding to the target wavelength λ, according to a pre-calibrated relationship between target resistance values and the target wavelength λ,
the relationship between target resistance values and the target wavelength λ comprises R 1 =(λ−λ 0 )/k 1 +R 01 and R 2 =(λ−λ 0 )/k 2 +R 02 where λ 0 is an initial wavelength, k 1 and k 2 are fitting coefficients of a relationship between a resistance change ΔR of the two thermistors and a wavelength drift Δλ=λ−λ 0 , respectively, and R 01 and R 02 are initial resistance values of the two thermistors corresponding to the initial wavelength λ 0 respectively, and
the wavelength selection method further comprises:
obtaining the fitting coefficients of the relationship between the resistance change ΔR of the two thermistors and the wavelength drift Δλ by:
changing the currents in the heating components, disposed on the first and second wavelength selection components, respectively, to change the wavelength of the outputted laser beam;
testing and recording several different wavelength values and the resistance values of the thermistors corresponding to the wavelength values, respectively;
calculating several wavelength drifts Δλ of the different wavelength values and the resistance changes ΔR corresponding to the wavelength drifts; and
linear fitting of several different wavelength drifts Δλ and the corresponding resistance changes ΔR to obtain a linear relationship Δλ=k*ΔR, and then obtaining the fitting coefficient of the relationship between the resistance change ΔR and the wavelength drift Δλ.

2. The wavelength selection method of claim 1 , wherein, the changing the currents in the heating components comprises increasing or decreasing the currents step by step.

3. The wavelength selection method of claim 1 , wherein the heating the heating components configured with the first and second wavelength selection components to control the temperatures of the first and second wavelength selection components until the real-time resistance values of the two thermistors reach the target resistance values R 1 and R 2 , respectively, comprises:
separately changing currents in the heating components on the first and second wavelength selection components and, at the same time, determining whether the real-time resistance values, r 1 and r 2 , of the two thermistors are equal to the target resistance values R 1 and R 2 , respectively;
in response to determining that the two real-time resistance values r 1 and r 2 are not equal to the target resistance values R 1 and R 2 , continuing to change the currents; and
in response to determining that the two real-time resistance values r 1 and r 2 are equal to the target resistance values R 1 and R 2 , respectively, stabilizing or fine-tuning the current values at this time to lock the real-time resistance values r 1 and r 2 at the target resistance values R 1 and R 2 , respectively.

4. The wavelength selection method of claim 1 , wherein the heating the heating components configured with the first and second wavelength selection components, respectively, to control the temperatures of the first and second wavelength selection components until the real-time resistance values of the two thermistors reach the target resistance values R 1 and R 2 , respectively, comprises:
searching for current values I 1 and I 2 in the two heating components that respectively correspond to the target resistance values R 1 and R 2 of the two thermistors among pre-stored resistance values corresponding to the wavelengths of all communication channels and their corresponding current values;
supplying currents that are equal to the current values I 1 and I 2 to the two heating components, respectively, and, at the same time, determining whether the real-time resistance values r 1 and r 2 of the two thermistors are equal to the target resistance values R 1 and R 2 , respectively;
in response to determining that the two real-time resistance values r 1 and r 2 are not equal to the target resistance values R 1 and R 2 , fine-tuning the currents until the two real-time resistance values r 1 and r 2 are equal to the target resistance values R 1 and R 2 , respectively; and
in response to determining that the real-time resistance values r 1 and r 2 are equal to the target resistance values R 1 and R 2 , respectively, stabilizing the current values at this time to lock the real-time resistance values, r 1 and r 2 , at the target resistance values R 1 and R 2 , respectively.

5. The wavelength selection method of claim 1 , wherein the step of heating the heating components configured with the first and second wavelength selection components to control the temperatures of the first and second wavelength selection components until the real-time resistance values of the two thermistors reach the target resistance values R 1 and R 2 , respectively, comprises:
calculating current values I 1 and I 2 that respectively correspond to the two target resistance values R 1 and R 2 , each of the current values I 1 and I 2 being calculated according to a pre-calibrated relationship between a resistance value R of the corresponding thermistor and the current I in the corresponding heating component: R=m*I 2 +R 0 , where R 0 is a calibrated value or the initial resistance value of the thermistor corresponding to an initial wavelength λ 0 , m is a fitting coefficients of a relationship between the resistance value R of the thermistor and the square of the current I 2 in the heating component;
supplying currents that are equal to the current values I 1 and I 2 to the two heating components, respectively, and, at the same time, determining whether the real-time resistance values, r 1 and r 2 , of the two thermistors are equal to the target resistance values R 1 and R 2 , respectively;
in response to determining that the two real-time resistance values r 1 and r 2 are not equal to the target resistance values R 1 and R 2 , fine-tuning the currents until the two real-time resistance values r 1 and r 2 are equal to the target resistance values R 1 and R 2 ; and
in response to determining that the two real-time resistance values r 1 and r 2 are equal to the target resistance val

Assignees

• Innolight Tech Suzhou Ltd

Inventors

• Luo Liang
• Tu Wenkai
• Gu Jinan

Classifications

• H01S3/10069 Primary

  Memorized or pre-programmed characteristics, e.g. look-up table [LUT] · CPC title

• H01S3/1305

  Feedback control systems · CPC title

• H01S5/0687

  Stabilising the frequency of the laser · CPC title

• G02F1/0147 Primary

  based on thermo-optic effects (G02F1/132 takes precedence) · CPC title

• H01S5/141 Primary

  using a wavelength selective device, e.g. a grating or etalon (H01S5/146 takes precedence) · CPC title