HERIOT-WATT UNIV EDINBURGH (SCOTLAND) DEPT OF PHYSICS

Nonlinear Refraction and Absorption of an InGaAs Single Quantum Well in an InGaAsP Waveguide,

22 MAY 1992

Authors: J. E. Ehrlich; D. J. Goodwill; D. T. Neilson; A. C. Walker; C. I. Johnston; HERIOT-WATT UNIV EDINBURGH (SCOTLAND) DEPT OF PHYSICS

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Semiconductor quantum-well structures can provide enhanced nonlinear effects compared to those observed in bulk material. The largest irradiance-induced refractive changes occur at wavelengths nearly resonant with the band edge or exciton absorption. If such a nonlinearity is to be effectively exploited in a waveguide configuration, the absorption due to the active quantum-well layers must be diluted to ensure sufficient transmission. Although this produces, all else being equal, a proportional drop ...

Two Dimensional Spatially Variant Optical Interconnects,

22 MAY 1992

Authors: E. J. Restall; B. Robertson; M. R. Taghizadeh; A. C. Walker; HERIOT-WATT UNIV EDINBURGH (SCOTLAND) DEPT OF PHYSICS

Spatially variant interconnects show great potential in the fields of optical computing and optical communications. Two dimensional forms of these interconnects offer even more power over their stacked one dimensional or wrap around counterparts. Several ingenious classical optical approaches exist to implement these complicated optical routing patterns, however all exhibit scalability and efficiency problems which make them unsuitable for use in a practical connection scheme. The interconnects we describe are ...

Passive Optical Array Generators,

22 MAY 1992

Authors: Mohammad R. Taghizadeh; Jari Turunen; Brian Robertson; HERIOT-WATT UNIV EDINBURGH (SCOTLAND) DEPT OF PHYSICS

Recent progress in designing and manufacturing space-invariant optical array generators is described. We begin by demonstrating Dammann gratings that generate even-numbered arrays as large as 128x128, and odd-numbered arrays of up to 201x201 spots. The concept of a hybrid hologram is applied to the fabrication of array generators, and extremely high-efficiency (close to 90%) components are obtained. Several novel types of array generators with multiple phase levels are introduced. These ...

Design and Construction of a Programmable Optical 16x16 Array Processor,

22 MAY 1992

Authors: A. C. Walker; R. G. Craig; D. J. McKnight; I. R. Redmond; J. F. Snowdon; HERIOT-WATT UNIV EDINBURGH (SCOTLAND) DEPT OF PHYSICS

There have been a number of significant advances in digital optical computing research over recent years. Experimental demonstrations of optical restoring logic, the lock-and clock control of data flow, a programmable optical logic unit, optical switching networks, and parallel logic modules have shown that the basic building blocks for a parallel digital optical computing system now exist. This paper describes recent work carried out at Heriot-Watt University in which such ...

Development of Microstructure During Extrusion of Rapidly Solidified Al- 7Mg-2Cr Powder Alloy

Authors: R. J. Dashwood; T. Sheppard; HERIOT-WATT UNIV EDINBURGH (SCOTLAND) DEPT OF PHYSICS

The microstructural development during extrusion has been studied in a rapidly solidified Al-7Mg-2Cr powder alloy. The microstructure was characterized using X-ray diffraction, TEM and DSC with respect to the consolidation conditions. Tensile yield strength and fracture toughness were determined as a function of the extrusion temperature. The best strength and toughness were obtained at 500 C.

Room-Temperature Optical Nonlinearities of Electronic Origin in ZnSe.

1990

Authors: W. Ji; J. R. Milward; A. K. Kar; B. S. Wherrett; C. R. Pidgeon; HERIOT-WATT UNIV EDINBURGH (SCOTLAND) DEPT OF PHYSICS

Nonlinear temporal transmission and degenerate four-wave mixing have been observed in polycrystalline ZnSe at room temperature. The nonlinear effects result from free carriers generated by nanosecond laser pulses of photon energies close to the band edge. Theoretical models are presented to describe both phenomena. The combination of experiments allows the refractive cross section to be measured. Comparison of theory and experiment verifies that the dynamic Burstein-Moss shift is the dominant ...

Optically Bistable Devices Using Semiconductor Materials

NOV 1984

Authors: S. D. Smith; M. E. Prise; C. T. Seaton; F. A. P. Tooley; C. R. Pidgeon; HERIOT-WATT UNIV EDINBURGH (SCOTLAND) DEPT OF PHYSICS

This report covers work conducted from February 1982 to February 1983 on the nonlinear optical properties of semiconductors using tunable (bandgap resonant) laser sources. Emphasis is on Carbon Monoxide (CO) Indium Antimonides (InSb) at 77K, but an optical parametric amplifier is constructed for future work on systems at shorter wavelengths. The Optical Bistability and device properties of InSb have been investigated. Operation of a slice of InSb, held at 77K, ...

Materials Suitable for Use in the Far Infrared.

MAR 1982

Authors: B. W. Davis; HERIOT-WATT UNIV EDINBURGH (SCOTLAND) DEPT OF PHYSICS

Submillimeter Laser and Fabry-Perot Spectroscopy Using Metallic Mesh

MAY 1981

Authors: C. R. Pidgeon; B. W. Davis; HERIOT-WATT UNIV EDINBURGH (SCOTLAND) DEPT OF PHYSICS

FREQUENCY DEPENDENCE OF TWO-PHOTON ABSORPTION IN INDIUM ANTIMONIDE AND MERCURY CADMIUM TELLURIDE.

1980

Authors: A. M. Johnston; C. R. Pidgeon; J. Dempsey; HERIOT-WATT UNIV EDINBURGH (SCOTLAND) DEPT OF PHYSICS

NONLINEAR REFRACTION AND ABSORPTION IN INDIUM ANTIMONIDE.

1979

Authors: G. D. Holah; J. Dempsey; D. A. B. Miller; B. S. Wherrett; A. Miller; HERIOT-WATT UNIV EDINBURGH (SCOTLAND) DEPT OF PHYSICS