Compact Diode Laser-Based Dual-Wavelength Master Oscillator Power Amplifier at 785 nm

A compact, micro integrated, diode laser-based dual-wavelength master oscillator power amplifier at 785 nm is presented. Laser emission from a V-branch distributed Bragg reflector laser is coupled into a tilted ridge waveguide amplifier on a 5 × 25 mm
²
micro optical bench. At 25°C and 20 mW pump power, an optical output power of 0.5 W is obtained. The corresponding emission wavelengths are 784.62 and 785.24 nm, resulting in a spectral distance of 10 cm
^-1
. The measured spectral bandwidths and side mode suppression ratios are 0.02 nm (0.3 cm
^-1
) and 30 dB, respectively. At both wavelengths beam propagation parameters of 1.3 (M
_4σ
²
) are obtained. This allows for efficient dual-wavelength single-mode fiber coupling. In addition, the device does not show any effects from optical feedback. It neither shows a lateral spatial tilt of the far field intensity distributions for the two wavelengths, previously reported for single V-branch diode lasers. Based on these parameters, the device is suitable for demanding applications such as shifted excitation Raman difference spectroscopy or confocal Raman microscopy.