Patent ID: 7844189

Claim:
An optical DPSK signal demodulator, comprising: a signal divider configured to divide a main optical signal into first and second optical signals; a first optical unit including: a first signal separator configured to receive the first optical signals and direct the first optical signals to a first optical path; a first reflector provided along the first optical path and proximate to the first signal separator, the first reflector being configured to receive the first optical signals and reflect the first optical signals toward the first signal separator, and a second reflector provided along the first optical path and distal to the first signal separator, the second reflector being configured to receive the first optical signals and reflect the first optical signals toward the first signal separator, a phase shifter provided along the first optical path and between the first and second reflectors, the phase shifter being configured to allow the first optical signals reflected from the first and second reflectors to have a phase difference, and a first output terminal configured to receive the first optical signals reflected by the first and second reflectors and output the first optical signals; and a second optical unit including: a second signal separator configured to receive the second optical signals and direct the second optical signals to a second optical path; a third reflector provided along the second optical path and proximate to the second signal separator, the third reflector being configured to receive the second optical signals and reflect the second optical signals toward the second signal separator, and a fourth reflector provided along the second optical path and distal to the second signal separator, the fourth reflector being configured to receive the second optical signals and reflect the second optical signals toward the second signal separator, and a second output terminal configured to receive the second optical signals reflected by the third and fourth reflectors and output the second optical signals, wherein the second optical signals reflected by the third and fourth reflectors and received by the second output terminal do not have a substantial phase difference.