| 摘要 |
PURPOSE: To simplify constitution and to contrive a low price of an optical transmission terminal station by providing both functions of polarized wave scrambling and monitoring control signal superposition in one device. CONSTITUTION: A phase modulator 10 is an optical phase modulator utilizing the electrooptic effect of crystal, and a linearly polarized wave of azimuth angle 45 deg. is inputted to an axis of polarization which supplies an ordinary ray refractive index to input signal light I(1) and to an axis of polarization which supplies an extraordinary ray refractive index to the same. In such a case, since a modulation signal V which drives the modulator 10 functions in an electric field, a driving part 2 can be constituted of an ordinary electronic circuit. Also, since a partial polarizer 3 is an optical element with polarization dependent permeability or polarization dependent reflectivity and is also a partial polarizer, no high polarization extinction ratio is required, the partial polarizer easily be realized. Further, when a data signal such as a monitoring control signal, etc., is superimposed on the modulation signal V, the intensity modulated light frequency on the output side of the polarizer 3 can be changed by changing its signal frequency depending on a data content, therefore, data can be superimposed on signal light to which the polarized wave scrambling is applied with intensity modulation. |
