| 摘要 |
PURPOSE:To control characteristics such as a hysteresis electric-current width, an oscillation threshold value and the differential quantum efficiency during a bistable operation by a method wherein a terminal to impress an electric current on a saturable absorption layer is installed, the electric current is impressed on the saturable absorption layer and a carrier density of the saturable absorption layer is controlled. CONSTITUTION:If a second electrode terminal 12 is biased as a positive side and a first electrode terminal 11 and a third electrode terminal 13 are biased as a negative side, this assembly functions as a bistable semiconductor laser which has two stable levels with reference to an input of an electric current. The electric current which is impressed on a second clad layer 9 from the electrode terminal 12 via a p-type impurity diffusion region 16 and a p-type electric-current impression layer 5 is divided into two parts for an active layer 8 and a saturable absorption layer 6 in accordance with a bias value at the electrode terminal 11 and the electrode terminal 13 and is then impressed on the two layers. The saturable absorption layer 6 functions as a loss of finite magnitude when a photon density or a carrier density is sufficiently small, and has a character that the loss non-linearly approached zero when the photon density or the carrier density becomes big to a certain extent. If a negative bias value to be impressed on the electrode terminal 13 is adjusted optimally, the carrier density of the saturable absorption layer 6 can be changed and the magnitude of the absorption loss can be controlled. |
