| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a phase-shift modulator which has a high sensitivity so as to respond a low control voltage and is independent of polarization, by specifying a structure of active waveguides of which each comprises at least one 1st active layer and one 2nd compensating active layer. SOLUTION: Active waveguides comprise at least one 1st active layer 11 and at least one 2nd compensating active layer 12. The materials Q1, Q2 composing each of these two layers 11, 12 are four-element material such as undoped InGaAsP. The 1st active layer 11 has a 1st photo-luminescence wavelength, and the 2nd compensating active layer 12 has a 2nd photo-luminescence wavelength, and the modulator operates at an operating wavelength longer than the 1st photo-luminescence wavelength by a value in a range of 80-200 nm (preferably 80-150 nm), and the operating wavelength is longer than that of the 2nd photo-luminescence by a value exceeding 300 nm (preferably 350 nm).</p> |
