In a planar-waveguide-type optical circuit 1, a reflection filter 4
is placed inside an oblique groove 3 formed to traverse optical waveguides
2n. Reflected light from the reflection filter 4 is detected
by photodetectors 61n of a photodetector array 6, and
thereby light intensity of signal light is monitored. A glass substrate made of
glass material having a refractive index substantially identical to that of a core
20 of the optical waveguide 2n and filter fixing resin
5 fixing the reflection filter 4 is used for a substrate 10
of the optical circuit 1 constituting part of the groove 3. This
inhibits reflection of light in various regions of the groove 3, thereby
reducing generation of extra scattered light inside the groove 3 and its
confinement. An optical waveguide module capable of enhancing monitoring characteristics
of the signal light is thus realized.
