| 摘要 |
PURPOSE:To obtain an orthogonal polarization type optical frequency shifter which uses a relatively inexpensive polarization beam splitter by providing the 1st polarization beam splitter, a two-channel acousto-optic element, and the 2nd polarization beam splitter. CONSTITUTION:An incident laser beam 31 is sent out while separated into 0-order light which travels straight and 1-order diffracted light 33 which is diffracted at an angle thetaB to the wave front of an ultrasonic wave signal, and the diffracted light 33 is utilized. This diffracted light 33 shifts a light signal by the center frequency of 81MHz of an acousto-optic element 21 under a transducer 24 and a light frequency is f1+81MHz. Then, this diffracted light 33 is incident on the 2nd polarization beam splitter 26, and reflected and sent out because of S polarized light. At this time, the 2nd polarization beam splitter 26 has a coupling function of P polarized light and S polarized light, so its projection light beam 34 has the P polarized light (light frequency: f1+80MHz) of diffracted light 32 and the S polarized light (light frequency: f1+81MHz) of the diffracted light 33 on the same optical path and two beams whose mutual frequency difference is 1MHz are obtained.
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