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

Based on wavelength beam combining, we use grating diffraction and external cavity feedback to lock all elements of the laser diode array(LDA) in different wavelengths, and the neighboring emitters have slight difference in locked wavelength. The output beam from the external cavity coupler mirror is nearly parallel with the same beam quality as single element of the LDA, and its brightness grows with the element number of the LDA increasing. The 1 cm linear array used in the experiment consists of 19 wide-aperture diodes with diode width of 100 μm and a fill factor is 0.2. When the free operating output power is 49.8 W and the maximal injection current is 60.6 A, the combined beam power is 20.1 W, the wavelength spread is about 15 nm, and the far field divergence angle varys from 70 mrad