| Wavelength locking is the most effective method to stabilize wavelength and narrow linewidth.Each emitter of diode laser array is locked at the same wavelength by feedback from the external cavity of VBG(Volume bragg grating).With the change of current and temperature,the wavelength drift of diode laser array is very small.Wavelength locking system of diode laser array can be used in laser pump,direct semiconductor laser system by wavelength combining,industrial,military and medical fields.The wavelength locking of diode laser array was studied by theoretical simulation analysis and experiment based on the structure and principle of wavelength locking of the external-cavity.Some critical problems,such as Smile effect,wavelength locking in the wide range of current and temperature in the external-cavity was solved.Wavelength locking system of diode laser array with high side mode suppression ratio(SMSR)is realized in the wide current and temperature range.Finally,a high-power diode laser fiber-coupling module with high stability,narrow linewidth and stable wavelength is developed.This article has presented the dual BTSs correct Smile in the wavelength locking system of diode laser array.The dual BTSs solves the problem that wavelength unlocking of diode laser array caused by larger residual divergence angle after collimation.In the process of wavelength locking of diode laser array,the Smile of diode laser array was corrected by dual BTSs,and the residual divergence angle after collimated and rotated was reduced.Therefore,the Smile adverse influence on wavelength locking of semiconductor laser array is reduced.At the same time,beam of semiconductor laser array in slow axis was transfored for the beam in the fast axis by dual BTS.In the slow axis,the collimation lens selection will not be limited by space position.The beam of semiconductor laser array in the fast and slow axis can be collimated well by BTS.It layed a foundation for fiber coupling of semiconductor laser array.In the theoretical simulation of the external cavity diode laser,a wavelength-locking model of external cavity diode laser array is proposed based on the transfer matrix and multi-mode rate equation.The external cavity structure of diode laser was divided into five parts,and the transfer matrix model of each part is established respectively in the theoretical simulation.Then whole transfer matrix model of the external cavity of semiconductor laser array is established.Through the principle of cavity equivalence,the external cavity of semiconductor laser is simplified and the theoretical model analysis is more convenient.According to the multi-mode rate equation of semiconductor laser,the change of side mode suppression ratio and power with temperature and current is simulated and analyzed.Based on theoretical simulation and experimental analysis,diode laser array with low reflectivity is experimentally studied to achieve wavelength locking in a wide range of current and temperature.According to the dual BTSs collimation structure,wavelength locking diode laser array with a front cavity surface reflectivity of 0.5%achieve the high side mode suppression ratio within the range of 15 A-50 A and15 ?-35 ?.The side mode suppression ratio of external cavity diode laser array is greater than 30 d B in a wide range of current and temperature.Based on the structure of the wavelength locking system,the output laser of semiconductor laser array with high power,narrow line width and high stability was fabricated. |
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