The selected research activities on integrated optics components and devices using periodic structures are reviewed, with emphasis on the authors' works employing the electron-beam writing technique. The periodic structures include static gratings and dynamic ones produced through acoustooptic (AO) and electrooptic (EO) effects. They provide a variety of passive functions and effective means for guided-wave control. The review is made from the integration point of view, including the most recent results. First, the theoretical fundamentals are outlined and the electron-beam writing techniques, including the writing system, are discussed. Next, passive components (grating deflectors, filters, lenses, couplers, etc.) and elements for guided-wave controlling and detecting (AO and EO grating elements and photodetectors) are described. Then, integrated optic devices, i.e., wavelength demultiplexers, RF spectrum analyzers, optical disk pickup, etc., are presented. Finally, the possibility of future applications is discussed.

Integrated optics components and devices using periodic structures

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 circuits and applications

TiO2, LiNb3O8, and (Ti065Nb035)O2 compounds have been observed and characterized during the fabrication of optical waveguides by Ti indiffusion in LiNbO3, performed in a flowing dry O2 atmosphere Ti oxidizes by reacting with both O atoms of the surrounding atmosphere and of the LiNbO3 substrate TiO2 formation is followed by LiNb3O8 and (Ti065Nb035)O2 phase growth With further increasing in the annealing temperature the TiO2 and LiNb3O8 compounds are consumed and vanish After 30 min at 950 °C both Y‐ and Z‐cut substrates appear covered only by a uniform and epitaxial (Ti065Nb035)O2 layer which behaves as the real source for Ti diffusion The LiNb3O8 formation and dissolution were also observed in samples uncoated with Ti Similar results were observed in LiNbO3 samples annealed in dry N, Ar, and static air

Characterization of TiO2, LiNb3O8, and (Ti0.65Nb0.35)O2 compound growth observed during Ti:LiNbO3 optical waveguide fabrication

Fabrication and characteristics of optical waveguides on LiNbO3

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.

Integrated acoustooptic and magnetooptic devices for optical information processing

This paper describes the integrated-optic implementation of a Bragg spectrum analyzer that employs the interaction between a coherent optical guided wave and a surface acoustic wave to determine the power spectral density of the input. The integrated-optic spectrum analyzer (IOSA) consists of an injection laser diode, a thin-film optical waveguide, waveguide lenses, a surface-acoustic-wave (SAW) transducer, and a linear detector array with CCD readout. Design principles are given for selecting component parameters such as optical beam width, detector cell size, lens aperture and focal length, and acoustic transducer design so as to obtain specific RF resolution, spurious level, and signal-to-noise ratio. Design parameters are presented for a 750-1250-MHz spectrum analyzer with a resolution of 4 MHz and a 40-dB dynamic range. Also described in the paper is the development of the state-of-the-art component technology for the spectrum analyzer.

M. Barnoski

Papers

Integrated-optic spectrum analyzer(Invited Paper)