Abstract: In an optical transmission system, a first modulated signal is generated at the transmitting end by modulating a first carrier signal with a first data signal and a second modulated signal is generated by modulating a second carrier signal, which differs from the first carrier signal by a differential frequency, with a second data signal. The first and second modulated signals are polarized orthogonally with respect to one another and combined to form an optical multiplex signal and are transmitted. At the receiving end, the optical multiplex signal is conducted via a polarization control element to a polarization splitter which splits the optical multiplex signal into the first and second modulated signals.

Abstract: To generate light with the degree of polarization zeroed and the spread of an optical spectrum suppressed even with temporal overlapping between optical pulses each of which is polarized orthogonally to the succeeding pulse, a polarization scrambler includes an optical pulse generator that generates optical pulses with an intensity waveform repetition period T/2 and an electrical field repetition period T in which the same intensity waveform is repeated every repetition period T/2 and in which phase is inverted every repetition period T/2, and an orthogonal polarization delay unit which receives each of the optical pulses, separates the optical pulse into two optical pulses with orthogonal states of polarization, and relatively shifts the temporal position of one of the two optical pulses from that of the other optical pulse by (2n−1)T/4 (n is a natural number) to generate light in which each pulse is polarized orthogonally to a succeeding pulse.

Abstract: A micro-optical delay element for a polarization time-division multiplexing scheme is disclosed wherein two light beams are provided to a polarization beam splitter/combiner (PBS/C) in the absence of optical fiber. At least one beam exiting a modulator is collimated and reaches the (PBS/C) unguided as a substantially collimated beam. In this manner the polarization state of the beam is substantially unchanged. This obviates a requirement for polarization controllers.

Abstract: A spread polarization transmitter for transmitting at least one light signal comprises a spread-spectrum communication apparatus and a polarization modulator. The spread-spectrum communication apparatus modulates the at least one light signal according to a spread-spectrum modulation technique. The polarization modulator comprises a polarizer and a magnetic bubble waveguide. The polarizer is capable of polarizing the at least one spread-spectrum modulated light signal in a polarized direction. And the magnetic bubble waveguide, which is configured in accordance with a pseudo-random polarization code sequence such that the plurality of magnetic bubble domains assume a time varying position representative of the pseudo-random polarization code sequence, is capable of receiving at least one polarized, spread-spectrum modulated light signal.