PHOTO MODULE

摘要

The purpose of the present invention is to provide a technique applied to a photo module for measuring signal strength in a transmission path in which signal light guided to the photo module is condensed on a light-receiving element without allowing reflected light from the photo module to re-enter the transmission path, the technique neither increasing the number of manufacturing steps nor increasing costs. The present invention is a photo module comprising an incident optical fiber (1) guiding incident light; a gradient index lens (2) having an optical axis (21) differing from that of the incident optical fiber (1), having a cycle length greater than one-quarter and less than one-half the wavelength of the incident light, and having as the emission plane of the emitted light a plane substantially perpendicular to the optical axis (21), the lens being joined to the incident optical fiber (1) on a plane at a finite angle to a plane perpendicular to the optical axis (21); and a light-receiving element (3) provided at the condensing position of the emitted light for measuring the strength of the emitted light.