| In the high power laser system, main amplifier usually uses Nd:glass medium whose working wavelength is 1053nm nearby, therefore the working wavelength of relevant seed source should be also in the same wave band. Comparing with current ytterbium-doped fiber laser,1.06μm tunable external cavity semiconductor laser has some advantages of small volume, direct current injection and high conversion efficiency. So it has some reference value in research of the alternatives of the front end system.Aiming at 1.06μm tunable external cavity semiconductor laser, numerical simulation and experiments have been done in this paper. First of all, rate equations of external cavity laser are used to simulate the wavelength tuning properties. The curve of P-I characteristic at different wavelengths and corresponding threshold currents are obtained. In the case of different operating currents, the output power relation curve which is changed with difference wavelengths is calculated. Secondly, tunable external cavity laser system of Littman type is set up. By adjusting focusing adjuster, the light spot after passing through lens is almost kept in the same size at different distance in a horizontal line during the adjustment of optical alignment. In order to ensure that the grating parallels the mirror for the better coupling, the first diffraction’s light spot and the second diffraction’s light spot are at the same horizontal line after some adjustments of the incident angle of grating and the pitch angle of plane mirror. Servo motor is fixed at a suitable position where its travel is match with wavelength tuning rang. Lastly, the software of the servo motor control of wavelength tuning is developed.In the experiments, wavelength calibration is made.3dB wavelength tuning range is about 35nm which is measured with 40mA and 60mA current injection respectively. The experimental curve of threshold current which is changed by the wavelength tuning is consistent with results of the numerical simulation. |
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