| 摘要 |
PURPOSE:To take a high erasion ratio at a low voltage, and to operate at a high speed by constituting the titled element of a semiconductor optical waveguide which contains a specific multiple quantum well structure and a layer on which a diffraction grating is formed, in a part of a waveguide layer and a clad layer, a means for applying an electric field, and a means for leading roughly vertically a light beam to each layer. CONSTITUTION:When a light beam 10a of lambda=1.32mum is made incident from on a mesa 7, at first, a diffraction grating 5 does not satisfy a Bragg condition, and the light beam passes through a substrate as it is and emitted as a light beam 10b. Subsequently, when a reverse bias is applied between electrodes 6, 8, an electric field is applied to a multiple quantum well (MQW) waveguide layer 3, an absorption coefficient increases against the light beam of lambda=1.32mum and the emitted light 10b starts an attenuation, and also. the Bragg condition is varied by a variation of a refractive index of the MQW, and in some electric field, the incident light 10a is couple to a waveguide light 10c, the emitted light 10c is decreased greatly, and a plane type optical gate element can be realized. In such a way, a large erasion ratio can be obtained without taking greatly an optical absorption length (MQW layer thickness), and as for an operation, speed, several GHz is obtained easily by reducing a CR time constant which is determined by an element capacity Q and a series resistance R. |
