| 摘要 |
PURPOSE:To transmit a signal by utilizing the frequency of beams by directly modulating a semiconductor laser. CONSTITUTION:Beams 32 projected from a semiconductor laser 30 are collimated by a lens 33, and the laser beams 34 are branched by a semitransparent mirror 35, and each diffracted by diffraction gratings 36, 37 and fed back to the laser 30, thus resulting in two longitudinal mode oscillation. The two oscillation frequency can be brought close by finely adjusting the driving currents of the laser and a laser mounting temperature. When a current amplitude modulation signal is applied to the laser 30 from a modulation circuit 42, two oscillation frequency is modulated, and transmitted over a fiber 40 as projected laser beams 39, transmitted beams by the fiber 40 are projected to a detector 41, and the beat signals of each oscillation beams are detected, thus transmitting informations. |
