| 摘要 |
PURPOSE:To maintain the output of the quantity of deflected light always at a constant level by detecting the light propagating in a thin film waveguide in an optical path, and controlling the output of a light source part in accordance with the quantity of the detected light. CONSTITUTION:The light emitted from a semiconductor laser 13 and propagating in a thin film optical waveguide 2 is paralleled by a thin film lens 14, and the parallel luminous fluxes are deflected by the diffraction effect caused by the ultrasonic surface elastic waves 7 excited by a comb toothlike electrode 6, and are again condensed by a thin film lens 9, thus forming deflected light 11 at the end face of the waveguide. At this time, a photodetector 12 detecting zero order diffracted light 20 is provided, and the electric signal obtained from this photodetector is fed back to the driving part of the laser 13, whereby the output of the quantity of th deflected light is corrected always to a constant level. |
