Accession Number : ADP007607

Title :   Nonlinear CDS Grating Coupler: C. W. and Pulsed Operation,

Corporate Author : ROME UNIV (ITALY)

Personal Author(s) : Bertolotti, M. ; Michelotti, F. ; Nisio, C. ; Fazio, E. ; Assanto, G.

Report Date : 22 MAY 1992

Pagination or Media Count : 1

Abstract : Distributed couplers, such as prisms and gratings, have been largely employed in conjunction with nonlinear planar waveguides in order to study the nonlinear properties of the structures, suitable for all optical devices in integrated optics. In the present work we report an experimental investigation of a semiconductor nonlinear grating coupler realized onto a planar linear waveguide, where the grating is burried between the guide and the substrate ( the periodicity is 0.8 microns) but over the guide in correspondence of the grating, there is a thin layer ( 200 A) of CdS. A single mode (Lambda = 0.632 microns) is supported by the guide while two modes are present if an Ar laser or the second harmonic of Nd-Yag pulsed laser is used. Radiation is coupled out through a prism . Input coupling effects have been studied in both temporal c.w. and pulsed regime versus input power. In c.w. operation all the obtained results are interpreted in terms of optothermal dispersive and absorbitive effects, while in the ps time domain electronic nonlinear behaviour of the CdS is the main responsible of the refractive index change of CdS.

Descriptors :   *WAVEGUIDE COUPLERS, *NONLINEAR OPTICS, ELECTRONICS, HARMONICS, INPUT, LASERS, OPERATION, OPTICS, PERIODIC VARIATIONS, POWER, PULSED LASERS, RADIATION, REFRACTIVE INDEX, SEMICONDUCTORS, STRUCTURES, TIME DOMAIN, SYMPOSIA, ITALY, CADMIUM SULFIDES, GRATINGS(SPECTRA), PULSED LASERS.

Subject Categories : Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE