| 摘要 |
PURPOSE:To make the temperature control of a semiconductor laser gentle, and make the amplification of a light input and the operation in a wide range of wavelength possible, by constituting a semiconductor laser in the manner in which an electrode is divided with a groove perpendicular to the direction of a resonator axis, and a high resistivity region whose depth does not reach an active layer is arranged in the semiconductor layer directly under the groove, and coupling the laser element with an optical fiber of input and output. CONSTITUTION:A p-InGaAs cap layer 14 and a p side electrode 16 are divided into two parts along a resonator axis by arranging a groove 17, and constitute electrodes 18 and 19. In order to make a region 30 directly under the groove 17, highly resistive, the most part of crystal in the cap layer 14 and a clad layer 13 of low refraction is destructed. Then the electrodes 18 and 19 operate almost independently, because the groove 17 is high resistive, so that a current is not injected into an InGaAsP active layer 12 directly under the groove 17. Accordingly, the dimension of a saturable absorption region which is a cause of hysteresis and differential gain characteristics in the input-output characteristics of light can be easily controlled by a current injection amont. A semiconductor layer 1 changes the state from OFF to ON by a small light input for the wavelength of a light input signal 20. At the time of laser oscillation, the loss in the saturable absorption region rapidly decreases by the injection of light, and the gain exceeds the loss on the whole. Thus a large light output can be obtained.
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