Tunable optical filter and external-resonator-type semiconductor laser device using the same

Abstract

In order to reduce the sizes of a tunable optical filter and an external-resonator-type tunable semiconductor laser device, the filter includes: a silicon substrate; a glass substrate which is disposed opposed to the face of the silicon substrate and is equipped with a transparent electrode layer provided over the face thereof disposed to the substrate; an optical diffracting-and-reflecting layer disposed over the face of the silicon substrate; and a liquid crystal layer disposed between the optical diffracting-and-reflecting layer and the transparent electrode layer; and the filter is characterized in that in the filter where the refractive index of the liquid crystal layer is controlled by the voltage applied between the silicon substrate and the transparent electrode layer, a silicon-substrate-side electrode terminal for applying the voltage thereto is provided on the backside of the silicon substrate, this filter being assembled in the external-resonator-type tunable semiconductor laser device.

Dependencies are inferred from the claim text.