Accession Number : ADP007867

Title :   Optical Nonlinearity through Internal Field Screening in Intrinsic Stark Effect Strained-Layer Superlattices,

Corporate Author : LOS ALAMOS NATIONAL LAB NM

Personal Author(s) : Watkins, D. E.. ; Sela, I. ; Laurich, B. K. ; Smith, D. L. ; Subbanna, S.

Report Date : 22 MAY 1992

Pagination or Media Count : 4

Abstract : A strong nonlinear optical effect has been predicted for strained-layer superlattices (SL's) grown with III-V semiconductors along axes other than 100. These materials have been denoted intrinsic Stark-effect superlattices (ISES) because the strain generates an electric field through the piezoelectric effect, and this field shifts the exciton resonance to lower energy and decreases the optical matrix element. Fields in excess of 105 V/cm have been theoretically predicted. In contrast SL's grown along the 100 axis should not exhibit any piezoelectric effect. Free carriers excited optically are expected to screen the internal field, shifting the exciton resonance to the blue and increasing the absorption cross section. A blue shift in the exciton resonance frequency has been observed recently by applying a reverse bias to a PIN diode with a 111 ga1 -xInxAs -GaAs SL structure in the intrinsic region. We report the first observation of optical nonlinearities due to free carrier screening of the intrinsic Stark effect fields in Ga1 -xInxAs - GaAs strained-layer superlattices. The strength of the nonlinearity due to this internal field screening (IFS) mechanism is compared to that due to exciton saturation by the phase space filling (PSF) mechanism, and we show that the former is much stronger.

Descriptors :   *EXCITONS, *PIEZOELECTRIC EFFECT, *STARK EFFECT, *SUPERLATTICES, *NONLINEAR OPTICS, ABSORPTION, ABSORPTION CROSS SECTIONS, AXES, BIAS, BLUE(COLOR), CONTRAST, CROSS SECTIONS, DIODES, ELECTRIC FIELDS, ENERGY, FREQUENCY, INTERNAL, LAYERS, MATERIALS, OBSERVATION, PIN DIODES, PHASE, RESONANCE, SATURATION, SEMICONDUCTORS, STRUCTURES, FREQUENCY SHIFT.

Subject Categories : Optics
      Electrooptical and Optoelectronic Devices

Distribution Statement : APPROVED FOR PUBLIC RELEASE