| 摘要 |
PURPOSE:To reduce a reactive current flowing into the circuit other than optical waveguide of the InGaAsP active layer and improve temperature characteristic by employing a P type InP substrate, N type InP current confinement layer, P type InP current blocking layer. CONSTITUTION:Since P type InP substrate 1 is used, an NPN transistor part sandwiches the InGaAsP active layer 5 having small band gap energy, efficiency of implanting electrons which are minor carriers to the P type InP clad layer 4 from the N type InP clad layer 6 is low and a current gain of NPN transistor is low. As a result, a switching voltage of pnpn layer becomes high and a current almost does not flow for a voltage applied during normal operation. As described above, a reactive current flows a little to the area other than the optical waveguide 5C of InGaAsP active layer. Therefore, good linearity of injected current-optical output can be obtained and a high output can also be obtained. Moreover, even when an oscillation threshold current density increases under a high temperature, increment of reactive current is small and good temperature characteristic can be obtained. |
