Patent ID: 6157752
Filing Date: 2000-12-05
Classification: H04B

Abstract:
A fiber optic link, comprising:an input coupler connectable to a source of laser energy, the input coupler configured to receive laser energy from the source divide received laser energy into two signals for transmission along two laser energy paths, impart a 90.degree. phase shift to one of the two signals, and output each signal along one of the two laser energy paths;a modulator including a first input connected to the input coupler for receiving laser energy traveling along a first one of the laser energy paths and a second input coupled to a source of modulating energy for receiving modulating energy, the modulator configured to modulate laser energy received from the input coupler with modulating energy to produce and output double-sideband suppressed-carrier signals;an output coupler having a first input connected to the modulator for receiving double-sideband suppressed-carrier signals produced by the modulator and a second input connected to the input coupler for receiving laser energy traveling along a second one of the laser energy paths, the output coupler configured (1) to impart a 90.degree. phase shift to laser energy traveling along the second laser energy path and combine this phase shifted laser energy with signals received from the modulator, (2) to impart a 90.degree. phase shift to signals received from the modulator and combine these phase shifted signals with laser energy traveling along the second laser energy path, and (3) to output the two combination signals; anda balanced receiver connected to the output coupler and having a first input for receiving one of the two combination signals produced by the output coupler and a second input for receiving the other of the two combination signals produced by the output coupler, the receiver configured to subtract signals received by the first input from signals received by the second input and output a resultant difference signal.