Abstract: A synchronization acquiring method capable of reducing the length of time required to perform in wireless communication a synchronization acquiring operation is provided when the mobile station transits from a sleep state to an active state. A synchronization acquiring apparatus capable of performing such a synchronization acquiring method is also provided. The method has the following three steps. In the first step, multiple correlation values are obtained between the input data supplied from a base station to the mobile station and multiple phases of a spreading code multiplied to the input data in the mobile station before the mobile station transits from the active state to the sleep state, multiple phases of the spreading code that correspond to the correlation values are determined, and the multiple phases are stored. In the second step, phases of the spreading code multiplied to the input data are determined using the phase when the mobile station transits from the sleep state to the active state.

Abstract: A multi-wavelength optical reflector comprises a diffraction grating structure (18) which comprises a plurality of repeat grating units (20) in which each grating unit (20) comprises a series of adjacent diffraction gratings (22, 24, 26) having the same pitch. The grating units (20) and adjacent gratings within a grating unit are separated by a phase change (28) of substantially pi (&pgr; radians). The lengths of the gratings (22, 24, 26), which are different for each grating within a grating unit, are selected so as to provide a predetermined comb reflection spectrum which comprises a plurality of reflection maxima of substantially equal reflectivity.