| 摘要 |
PURPOSE:To make two-way optical communication possible by only one optical fiber and semiconductor laser by modulating emitted light at the emission terminal side of the optical fiber corresponding to an information signal and then by feeding the modulated light to the semiconductor laser via the optical fiber from the emission terminal side. CONSTITUTION:Signal A to be transmitted to terminal 21 is applied and modulated by pulse modulator 22 into a modulated signal, which is applied to semiconductor laser 24. Radiated laser light 25 from laser 24 is coupled with optical fiber 27 via coupling circuit 26 and then strikes photo detector 29 by way of focusing optical system 28 at the emission side and half mirror 32. The electric output of detector 29 is passed through demodulator 30 to output signal A. Of the laser light emitted from optical system 28, light reflected by mirror 32 is reflected by reflex mirror 33 and strikes fiber 27 again to obtain feedback light 35, which strikes laser 24. Modulator 40 is applied with signal B and chopper 38 is driven by its output to modulate feedback light 35 by signal B; and the demodulated light is detected by photo detector 37 and after feedback light 36 is separated by a filter, it is inputted to demodulator 41 to obtain signal B. |
