Monolithic Y-branch dual wavelength DBR diode laser at 671 nm for shifted excitation Raman difference spectroscopy

In this work a monolithic Y-branch dual wavelength distributed Bragg reflector (DBR) diode laser with an emission at 671 nm for SERDS (shifted excitation Raman difference spectroscopy) is presented. The device has a footprint of 0.5 mm x 3 mm and consists of two laser cavities. Two ridge waveguide (RW) sections with different deeply etched surface DBR gratings are realized. The DBR mirrors were designed with respect to the necessary spectral spacing of 10 cm^-1. A Y-branch coupler section is implemented in the semiconductor chip for the realization of one output aperture at the front facet to avoid a spatial separation of the excitation spot on the sample. Individual electrical contacts at all sections allow a separate trigger for both excitation wavelengths.