Wavelength beam combining of a laser diode array to get 20 W cw circle spot emission

Based on the wavelength beam combining technology,we use the diffraction of the grating and the feedback of the external cavity to lock all elements of a laser diode array(LDA)on different wavelengths.The beam quality of LDA is improved and a near parallel output is produced in the direction of-1 order diffraction of grating.A commercial available LDA with 19 emitters is apllied,whose size is about 1 cm.The period of the LDA is 500 μm and the width of emitters is 100 μm.With a maximum continuous injection current of 60.6 A,the output free running power is 49.8 W,and a steady beam combined output power of 20.1 W is obtained.The width of spectrum is 15 nm.And the far-field divergence angle is reduced from 70 mrad to 1.66 mrad.The improved bem quality M2x,y is about 32,which is almost equal to that of a single emitter.