INTEGRATED OPTICAL TIME DELAY UNIT

PROBLEM TO BE SOLVED: To obtain a true time delay(TTD) system for an optical signal whose package size is reduced which is suitable for escaping beam squint in wide band application by constituting a TTD system so as to be integrated on a planar silica waveguide. SOLUTION: A TTD system 36 is formed as a silica-planer waveguide. Thus, the package size of this device can be reduced. The TTD system 36 includes an input port 1 and output port 3. An optical fiber core is displaced with an optical wave guide formed of a polarization beam splitter 38, input leg part 40, 1/4 wave polarization rotator 42, and spiral waveguide part 44. The spiral waveguide part 44 is formed so that polarization can be preserved. Bragg grids 48 are provided with different intervals for different wavelength along the spiral waveguide part 44 so that any time delay can be substantially attained.