Wavelength selection method and wavelength selection device for tunable laser

A wavelength selection device in a tunable laser, comprising:

• at least two thermally tunable wavelength selection components on an optical path, the at least two thermally tunable wavelength selection components including a first wavelength selection component and a second wavelength selection component;
• and
• a control component, comprising:
• a controller;
• a storage device;
• a first heating component to heat the first wavelength selection component;
• a second heating component to heat the second wavelength selection component;
• a first thermistor to monitor the first wavelength selection component;
• and
• a second thermistor to monitor the second wavelength selection component,
• wherein:
• the storage device is configured to pre-store a relationship between target resistance values of the first and second thermistors and a target wavelength λ:
• R1=(λ−λ0)/k1+R01 and R2=(λ−λ0)/k2+R02, where λ0 is an initial wavelength, k1 and k2 are fitting coefficients of a relationship between a resistance change ΔR of the first and second thermistors and a wavelength drift Δλ=λ−λ0, respectively, and R01 and R02 are initial resistance values of the first and second thermistors corresponding to the initial wavelength λ0, respectively, and,
• the controller is configured to:
• calculate and lock the target resistance values R1 and R2 of the first thermistor and the second thermistor, respectively, corresponding to the target wavelength λ by using data stored in the storage device;
• and
• stabilize real-time resistance values of the first thermistor and the second thermistor, respectively, at the target resistance values R1 and R2 by controlling currents in the first heating component and the second heating component,
• wherein the storage device is configured to pre-store a pre-calibrated relationship between a resistance value R of the corresponding one of the first and second thermistors and a current I in the corresponding one of the first and second heating components:
• R=m*I2+R0, where R0 is a calibrated value or the initial resistance value of the thermistor corresponding to the initial wavelength λ0, m is a fitting coefficient of the relationship between the resistance value R of the thermistor and the square of the current I2 in the heating component, and
• the controller is configured to:
• calculate current values I1 and I2 that respectively correspond to the two target resistance values R1 and R2 each of the current values I1 and I2 being calculated according to the relationship between the resistance value R and the current I;
• and
• supply currents that are equal to the current values I1 and I2 to the first heating component and the second heating component, respectively.

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 R1 and R2 of the two thermistors, respectively configured with the first and second wavelength selection components, respectively corresponding to the target wavelength λ;
• obtaining currents values I1 and I2 in the two heating components, respectively configured with the first and second wavelength selection components, respectively corresponding to the target resistance values of the two thermistor;
• supplying currents that are equal to the current values I1 and I2 to the two heating components, respectively, and, at the same time, determining whether real-time resistance values r1 and r2 of the two thermistors are equal to the target resistance values R1 and R2, respectively;
• in response to determining that the two real-time resistance values r1 and r2 are not equal to the target resistance values R1 and R2, fine-tuning the currents until the two real-time resistance values r1 and r2 are equal to the target resistance values R1 and R2;
• and
• in response to determining that the two real-time resistance values r1 and r2 are equal to the target resistance values R1 and R2, respectively, stabilizing the current values at this time to lock the real-time resistance values r1 and r2 at the target resistance values R1 and R2, respectively, and outputting a laser beam having the target wavelength λ.