| 摘要 |
PURPOSE:To enable frequency modulation having a large frequency deviation by using a light source having high spectral purity by attaching an external resonator to a semiconductor laser and modulating frequency by utilizing the mode jumping of an external resonator mode by changing injection currents to the semiconductor laser. CONSTITUTION:Beams 2 projected from the rear end surface of a Fabry-Perot type semiconductor laser 1 are collimated by a lens 3, and fed back to the semiconductor laser 1 by a diffraction grating 4. Consequently, the simple substance of the semiconductor laser 1 multi-axial mode oscillates, but it single- axial mode oscillates by the wavelength selectivity of the diffraction grating 4, and sufficiently narrow spectral line width such as 100kHz is acquired. A DC bias circuit 5 is adjusted, and a bias level is set previously immediately before the semiconductor laser 1 mode-jumps at an external resonator mode. When a fine modulation signal is transmitted over the semiconductor laser 1 through a signal generator 6 and a driver 7, the semiconductor laser 1 repeats mode jumps in response to the modulation currents, and binary frequency modulation can be applied to output beams 8 from the semiconductor laser 1. |
