| 摘要 |
PROBLEM TO BE SOLVED: To obtain an improved analog optical system which imparts an improved dynamic range and sensitivity by impressing plural lasers having different wavelengths to a Mach-Zehnder modulator by a wavelength division mutiplexer. SOLUTION: This analog optical link includes a Mach-Zehnder modulator 20. The Mach-Zehnder modulator 20 is operated at a low bias point in order to improve the sensitivity and simultaneously has the different wavelengths for the purpose of offsetting the distortion of even order associated with a low bias and, therefore, uses two light carriers at two effective bias points. A bias control circuit 50 controls the two wavelengths so as to simultaneously bias the Mach-Zehnder modulator 20 at the minimum bias point where the equal gains having opposite codes are given. These wavelengths may be given by the two separate lasers 42 and 44 giving the discrete light carriers. The two lasers 42 and 44 are the lasers of the equal power having the different wavelengths λ1 and λ2 and are combined by the wavelength division multiplexer 46. |
