Hamamatsu Photonics K.K. 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.
The results of this research were published in the electronic version of Applied Physics Express (APEX) Online on the 14th April 2015, and will appear in the May issue of the publication. In addition, an oral presentation will be given at OPIC 2015 (Optics & Photonics International Congress) in Japan on the 23rd April 2015.
*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.