| 摘要 |
PCT No. PCT/GB91/02133 Sec. 371 Date May 19, 1993 Sec. 102(e) Date May 19, 1993 PCT Filed Dec. 2, 1991 PCT Pub. No. WO92/11562 PCT Pub. Date Jul. 9, 1992.An optical mixing device (10) incorporates a rectangular multimode waveguide (14), with an input region (22) and an output region (24), two square section input waveguides (26, 28), and a detector (34). The input waveguides (26, 28) are arranged to provide first and second input radiation beams respectively to the input region (22), each beam being in the form of a square waveguide fundamental mode beam. Modal dispersion along the multimode waveguide (14) produces a single maximum incident on the detector (34) when the input beams are in phase with one another, and two maxima of like magnitude located on opposite sides of the detector (34) when the input beams are in antiphase. Intermediate these two situations three maxima are produced, the amplitudes depending on phase difference. The first and second input beams may be of like frequency producing a time-independent device output. The input beams may alternatively have different frequencies. For instance the first input beam may be a local oscillator signal produced by a coherent source of stable frequency, and the second input beam may be a Doppler shifted version of an output signal from that source. The device output then provides an intermediate frequency signal. The intensity incident on the detector (34) thus varies at the difference frequency of the two inputs. Similar devices may be constructed with additional inputs and with different forms of output.
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