Semiconductor optical modulator

• Main Author: ISHIMURA; EITARO
• Format: Patent
• Language: English
• Published: 28.05.1996
• Edition: 6
• Subjects: BASIC ELECTRIC ELEMENTS; DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; DEVICES USING STIMULATED EMISSION; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL LOGIC ELEMENTS; OPTICS; PHYSICS; SEMICONDUCTOR DEVICES; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF

A semiconductor optical modulator includes a light absorbing layer having a multi-quantum well structure including two quantum wells including quantum well layers bounded and separated by barrier layers, the quantum wells having respective, different DELTA Ev/ DELTA Ec ratios where DELTA Ec is the discontinuity between the barrier layer and a quantum well layer in the conduction band edge and DELTA Ev is the discontinuity between the barrier layer and a quantum well layer in the valence band edge. By this construction, the absorption peak when no electric field is applied significantly shifts toward the longer wavelength side, resulting in a large difference between the absorption peak wavelength when no electric field is applied and the absorption peak wavelength when an electric field is applied, whereby the absorption loss of a semiconductor optical modulator when no electric field is applied is reduced.