| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a high-speed and polarization independent lithium niobate modulator which is little in insertion loss, low in driving voltage and high in speed. SOLUTION: At least three electrodes and first and second lithium niobate optical waveguides arranged between these electrodes are included in the optical modulator. The first optical waveguide receives an optical communication path signal and the second optical waveguide outputs an optical output communication path signal. A cross connecting/delay line interconnects the second end of the first optical waveguide and the first end of the second optical waveguide respectively by polarization maintaining optical fibers and introduces a prescribed rotation in a TE mode and a TM mode. Consequently, the polarization component at the second end of the second optical waveguide receives the phase modulation of the same quantity. While the three electrodes arranged in another type having the first and second optical waveguides are included in the modulator, five electrodes are included therein. The first and second optical waveguides are divided into two parallel branch lines positioned between the single one set and the five electrodes.</p> |
