Hamamatsu Photonics has developed the wavelength beam-combining laser diode (LD) with a narrow spectral bandwidth of less than one eighth. This development was achieved by controlling the wavelength from two high-power LD stacks at the same time using a stripe mirror and single plane type VBG* (Volume Bragg Grating). This exciting new advancement may lead to the development of an excitation LD light source that improves the performance of all solid-state lasers.
*VBG: Optical devices with a Bragg grating strongly diffract the light in a specific direction by periodic slight changes in the refractive index inside the photothermorefractive glass with photo-induced refractive index (photorefractive). The narrow bandwidth light is strongly reflected in only a specific direction, with almost no light reflected at any angle other than the one specified. It improves LD’s horizontal and vertical modes, and realises stable wavelength and narrow bandwidth.