Fundamental evaluation of semiconductor waveguide-type in-line wavelength selective filter with Fabry-Perot etalon resonator

As compact filtering devices easily integrated with semiconductor waveguides and also for the application to a multi-wavelength light source, we fabricated an InGaAsP/InP semiconductor waveguide-type in-line wavelength selective filter with a Fabry-Perot etalon resonator. A filtering effect was obtained with an almost-designed transmission wavelength interval of 0.8 nm. Fundamental characteristics of the fabricated devices were evaluated, and structures to improve the contrast ratio are discussed.