Patent ID: 6560021
Filing Date: 2003-05-06
Classification: G02B

Abstract:
A variable optical wavelength filter comprising:an optical wavelength filtering portion having an optical wavelength filter for selecting the specific wavelength for providing the maximum transmission peak to an optical output signal from the wavelengths of an optical input signal; and an optical wavelength filter control system for outputting to said optical wavelength filtering portion a control signal comprising: a direct current movement signal for moving said optical wavelength filter to a position for selecting said optical output signal with said specific wavelength according to wavelength variation of said optical input signal; and an alternating current detection signal for providing an amplitude frequency to said optical output signal by slightly vibrating said optical wavelength filter at a fixed detection frequency; wherein said optical wavelength filter control system comprises: an optical wavelength filter control portion including a direct current component forming portion for sustaining the output of said direct current movement signal even during a momentary loss of said optical input signal, while determining the size of said direct current movement signal on the basis of the amplitude of said optical output signal; and an alternating current detection signal generator for outputting said alternating current detection signal at said detection frequency.