Lightwave switching is discussed with a cascaded connection of optical couplers with light intensity control elements. By employing wavelength-selective amplifiers such as a waveguide-type Raman amplifier, all-optical wavelength-selective switching can be realized. We discuss analytically using coupled-mode theory that the lightwave switching is feasible by controlling the intensity of propagating lightwave. The switching operation is verified numerically using finite-difference beam-propagation method. As a result, the expected operation is realized and some characteristics involved with dependencies of wavelength and phase are also investigated. A preliminary experiment using attenuators, beam splitters and mirrors is also described to verify the switching operation with only light-intensity control in interferometers.

Switching characteristics such as wavelength dependency and phase dependency are investigated for our proposed switch which consists of waveguide-type Raman amplifiers and 3-dB couplers. As a result, the available range of wavelength and phase shift due to nonlinear effect are estimated about 20 nm around 1.55 µm and about 10 degrees, respectively.