G. R. Dubois

Bio: G. R. Dubois is an academic researcher from University of Toronto. The author has contributed to research in topics: Simple lens & Cardinal point. The author has an hindex of 1, co-authored 2 publications receiving 9 citations.

Evaluation of an integrated acousto-optic receiver

Abstract: Various measurements pertinent to the development of an integrated acousto-optic receiver (spectrum analyzer) are considered. The developed receiver employs three tilted, uniform transducers to provide a 3 dB operating bandwidth of 141 MHz centered at 151 MHz. The three elements were phased acoustically eliminating the need for electrical phase matching networks. The receiver utilizes external optics, and has Rayleigh criterion resolution of 2 MHz.

Geodesic lenses for integrated optics

Abstract: The design and fabrication procedure for an aberration-free, rounded-edge waveguide geodesic lens is described. This paper concludes that in any system using a geodesic lens, the precise position of the focal plane will have to be determined after the lens fabrication.

Integrated acoustooptic circuits and applications

Abstract: The recent development of titanium-indiffusion proton-exchange (TIPE) microlenses and lens arrays has made possible the construction of a variety of single- and multichannel integrated acoustooptic (AO) and acoustooptic-electrooptic (EO) circuits in LiNbO/sub 3/ channel-planar waveguides 0.1*1.0*2.0 cm/sup 3/ in size. These hybrid AO and AO-EO circuits can be fabricated through compatible and well-established technologies. The most recent realization of ion-milled microlenses and lens arrays together with the recent development of gigahertz AO Bragg modulators and EO Bragg modulator arrays have also paved the way for construction of similar but monolithic AO and AO-EO GaAs/GaAlAs waveguides of comparable size. Both types of integrated AO and AO-EO circuits suggest versatile applications in communications signal processing, and computing. Efficient and simultaneous excitation of the channel waveguide array using an ion-milled planar microlens array has facilitated the demonstration of some of these applications. >

Integrated acoustooptic and magnetooptic devices for optical information processing

Abstract: Acoustooptic (AO) Bragg interactions between guided optical waves and surface acoustic waves (SAW's) and the resulting AO Bragg cell modulators have evolved in integrated AO technology in recent years. A variety of hybrid multichannel integrated AO device modules including power and interferometric RF spectrum analyzers, space switches, tunable filters, frequency shifters and modulators, analog algebraic processors, programmable correlators and other multichannel device modules have been realized in common LiNbO/sub 3/ substrate up to 1.0/spl times/3.7 cm/sup 2/ in maximum size. The prospects for realization of their counterparts in monolithic integrated format in a common substrate of InGaAsP material system are also significantly enhanced recently. These AO device modules have shown a high degree of modularity and suggested applications in optical information processing and communications. In the meantime, the magnetooptic (MO) Bragg interactions between guided optical waves and magnetostatic waves (MSWs) in yttrium iron garnet-gadolinium gallium garnet (YIG-GGG) waveguides have resulted in miniaturized MO Bragg cell modulators in analogy with the guided-wave AO Bragg cell modulators. Most recently the performance of such MO Bragg cell modulators has been significantly improved and the modulators have been integrated with ion-milled waveguide lenses to realize hybrid integrated MO device modules, and have been utilized to demonstrate a number of novel applications. In this paper, a review of some of these integrated AO and MO device modules and applications together with some unpublished new results are presented.

An integrated optic RE spectrum analyzer in a ZnO-GaAs-AlGaAs waveguides

Abstract: A report is presented on the realization of an integrated optic RF spectrum analyzer (IOSA) that combines a wideband acoustooptic Bragg cell and a pair of waveguide lenses in ZnO/GaAs/Al/sub 0.15/Ga/sub 0.85/As composite waveguide 7*23 mm/sup 2/ in size. A total of 10 and 40 channels at the center frequencies of 167 MHz and 500 MHz, respectively, and a frequency resolution of 5.5 MHz were realized. The diffraction efficiencies of 11.5%/W and 4.0%/W of RF drive power at the center frequencies of 167 MHz and 500 MHz, respectively, and a dynamic range larger than 16 dB were measured. Further integration of this IOSA (integrated optic spectrum analyzer) with a laser source, a photodetector array, and electronic driving circuits could produce a monolithically integrated optic RF spectrum analyzer. >

Wideband Acousto-Optic Bragg Diffraction in LiNbO 3 Waveguide and Applications

Abstract: Chapter 2 has presented the basic principles and analytical techniques for bulk-wave Acousto-Optic (AO) interactions. In this chapter, a detailed treatment of wide-band AO Bragg diffraction in a planar LiNbO3 waveguide, the resulting devices, and some potential applications is given. The sequence of presentation for the content of the Chapter now follows. First, the basic configuration and mechanisms for planar guided-wave AO Bragg diffraction from a single Surface Acoustic Wave (SAW) in a LiNbO3 waveguide and the resulting diffraction efficiency and frequency response are analyzed in detail using the coupled-mode technique. As a comparison some calculated and measured performances with the other two potential materials, namely GaAs and nonpiezoelectrics such as thermally-oxidized Si or AS2S3, are also discussed. The key parameters of the resulting AO Bragg modulators and deflectors or cells and their inherent limitations are then identified and discussed. The coupled-mode technique is thereafter extended to analyze AO Bragg diffraction from multiple SAWs. The unified theory developed is applied to the two wide-band device configurations, namely, multiple tilted SAWs and phased SAWs. Subsequently, a number of SAW transducer configurations for realization of wide-band Bragg cells are described and compared. Design, fabrication, testing, and measured performance of wide-band AO Bragg cells in y-cut LiNbO3 substrates are also presented.

Elastic constants of lithium niobate

Abstract: All the elastic constants of lithium niobate have been determined from specimens prepared from Z-cut plates only, using a series resonance method. New approaches are followed for the evaluation of stiffness constants C12, C13 and C14 using a bar specimen. It is shown that the same ZX-cut bars can be utilized for measurements of the stiffness constants C11, C13 and C14.