OPTICAL WAVE SAFTY CIRCUIT OF LASER DIODE IN WAVE-LENGTH DIVISION MULTIPLEXING SYSTEM

摘要

PURPOSE: An apparatus for stabilizing light wavelength of a laser diode is to automatically stabilize the light wavelength of the laser diode using a simple circuit when turning on a WDM(wavelength division multiplexing) system, thereby simplifying a structure of the system. CONSTITUTION: An FBG(fiber bragg grating)(21) generates a reference wavelength for stabilizing a light signal. A tap coupler(22) taps a difference between light wavelength of a laser diode and the reference wavelength of the FBG into a desired percentage. A photo-detecting portion(23) detects the light wavelength tapped by the tap coupler and then converts into an electric signal. A differentiator(24) differentiates the electric signal with respect to time. An amplifying portion(25) amplifies the differentiated value generated from the differentiator. The first comparing portion(26) generates a pulse according to polarity of the amplified value. A window comparing portion(27) generates a pulse according to whether an initial light wavelength of the laser diode is included in a dead zone which is a limit value of the wavelength of the laser diode. An adding portion(28) adds the pulse generated from the first comparing portion and the window comparing portion.