MULTIPLE QUANTUM WELL OPTICAL MODULATION ELEMENT

摘要

PURPOSE: To provide the multiple quantum well optical modulation element of the external modulation type suitable for the optical fiber communications capable of performing the optical modulation without deteriorating the quenching ratio in the high-speed modulation or the luminous intensity of high input light. ;CONSTITUTION: A multiple quantum well area (light absorbing layer) 20 includes quantum wells 22₁, 22_n-1, 22_n, 22_n that alternate with barrier layers 21₁, 21₂, 21_n. The light passing through the light absorbing layer 20 is modulated by selectively making the light absorbing layer 20 transparent or absorptive against the wavelength of incoming light. The quantum wells 22₁, 22_n-1, and 22_n, and 22_n+1 of the light absorbing layer 20 have more than three quantum levels. The quantum well structure is set to produce the same bias voltage in the resonance tunnel placed between the 1st and 2nd quantum levels and in the resonance tunnel placed between the 2nd and the 3rd quantum levels between the adjacent quantum wells.;COPYRIGHT: (C)1994,JPO&Japio