초록 ▼

The present invention detects the difference in phase between the modulation of a received optical beam and a reference RF signal or a second modulated optical beam. The received optical beam is modulated by the reference signal and by this reference signal phase shifted 90 degrees. The difference c

The present invention detects the difference in phase between the modulation of a received optical beam and a reference RF signal or a second modulated optical beam. The received optical beam is modulated by the reference signal and by this reference signal phase shifted 90 degrees. The difference cross modulation in these two modulated optical beams is detected. The phase difference to be detected is formed by dividing the difference cross modulation of the modulated second optical beam by the difference cross modulation of the modulated first optical beam. This quotient is proportional to the tangent of the phase difference to be detected. The optical modulation can be achieved by bulk electro-optic modulators operating on split beams, by a bulk electro-optic modulator alternatively modulating a single beam by the reference signal and the phase shifted version of the reference signal, or by changing the coupling between two parallel, matched wave guides in an integrated optic device. This system is useful in elimination of amplitude-phase cross talk in phase shift modulation optical communications systems and in three dimensional optical ranging systems.

대표청구항 ▼

A method for detecting the phase difference between a reference RF signal and the modulation of a received optical beam comprising: modulating said received optical beam by the reference RF signal thereby producing an RF modulated first optical beam; detecting the first difference cross modulation i

A method for detecting the phase difference between a reference RF signal and the modulation of a received optical beam comprising: modulating said received optical beam by the reference RF signal thereby producing an RF modulated first optical beam; detecting the first difference cross modulation in said RF modulated first optical beam between the modulation of the received optical beam and said modulation by the reference RF signal; generating a phase shift reference RF signal having a ninety degree phase shift from the reference RF signal; modulating said received optical beam by the phase shift reference RF signal thereby producing an RF modulated second optical beam; detecting the second difference cross modulation in said RF modulated second optical beam between the modulation of the received optical beam and said modulation by the phase shift reference RF signal; dividing the second difference cross modulation of said RF modulated second optical beam by the first difference cross modulation of said RF modulated first optical beam, said quotient being proportional to tangent of the phase difference to be detected.