| 摘要 |
PURPOSE:To obtain a semiconductor laser, which can be directly modulated at a super-high speed, by using a forward direction bias part as an optical active layer, and using a reverse direction bias part as a light absorbing layer, which can be modulated. CONSTITUTION:DC biases are applied to electrodes so that a part between 6 and 7 is forward biased and a part between 7 and 8 is reverse biased, i.e., 6 is negatively biased with respect to the electrode 7, and 8 is positively biased with respect to the electrode 7. Under this state, a part between an active layer 3 and a clad layer 4 is forward biased and a current is injected to the active layer 3. The active layer 3 has a gain with respect to light. Meanwhile, since a part between 1 and 3 is reverse biased, a high electric field is applied to a high resistance layer 2, and light absorption occurs due to electric field absorption. The light is guided along both the layers 2 and 3. Therefore, the light, which is reciprocated in the direction of a resonator, receives a net gain corresponding to the difference between the gain of the active layer 3 and the absorption of the layer 2. When the net gain is equal to the loss of the resonator, the laser is in the steady oscillating state. When the gain is larger than the loss, the light output is increased. When the gain is small, the light output is decreased. Under the state, the DC bias is imparted to each electrode, a modulating current is applied to the electrode 7, and modulation is carried out. |
