A wideband electronically tunable microwave notch (band-stop) filter has been constructed in an yttrium iron garnet (YIG)/gallium arsenide (GaAs) material structure An incident microwave propagating along the microstrip transmission line in the GaAs substrate is coupled into and to excite the magnetostatic surface waves in the YIG layer, which is laid upon the microstrip transmission line Maximum coupling and thus the peak absorption of the output microwave power occur at the ferromagnetic resonance frequency in the YIG film as determined by a bias magnetic field A tuning range as large as 25–230 GHz in the peak absorption frequency with the corresponding magnetic field tuning range of 290–7300 Oe has been accomplished Peak absorption of 15–38 dB in the microwave output power has also been measured

A wideband electronically tunable microwave notch filter in yttrium iron garnet–gallium arsenide material structure

This chapter reviews the materials and devices used in thin film technology. Thin films have been used for more than a half century in making electronic devices, optical coatings, instrument hard coatings, and decorative parts. Thin films are a low-dimensional material created by condensing, one-by-one, atomic/molecular/ionic species of matter on a substrate. The thickness of the film is less than several microns. A thick film is a low-dimensional material created by thinning a three-dimensional material or assembling large clusters/aggregates/ grains of atomic/molecular/ionic species. Thin film technology is developed for nanometer materials and/or a man-made superlattice. These materials and devices are also available for minimization of toxic materials since the quantity used is limited only to the surface, and saves on energy consumption in production. Thin film technology is both an old and a current key material technology.

1 – Thin Film Materials and Devices

We propose a novel high-speed magnetooptic (MO) modulator based on the optical excitation of surface magneto-plasmon (SMP) waves in bismuth-substituted yttrium iron garnet (Bi-YIG). A model describing magnetization dynamics of the Bi-YIG film is used in conjunction with an SMP reflectivity model to evaluate the performance of the device. In developing the reflectivity model, the dispersion relation for the SMP waves at a Bi-YIG-metal interface is derived. The optical response of the device is modeled for various driving pulses, and the performance of the device is discussed in terms of response time, efficiency, and bandwidth. Using practical material parameters, it is found that the modulator has an improved efficiency over MO modulation devices relying on bulk propagation for comparable driving current pulse durations, as well as the added benefits of a miniature design, multigigahertz operation, and tunable bandwidth. The analysis presented here provides a useful framework for the design and development of magneto-plasmon photonic devices.

A gigahertz surface magneto-plasmon optical modulator

The origin of Li deficiency in films grown by laser ablation of single-crystal LiNbO3 targets in a buffer gas has been investigated by analyzing the stoichiometry of the deposited films as a function of the following parameters: the distance target-substrate, the nature of the buffer gas (He, O2, and Ar) and the deposition configuration. The results show that significant Li losses are related to scattering processes during the expansion regime which are higher the higher the mass of the gas species. The results show that the Li content of the films can be enhanced by setting the substrate either at distances larger than the plume length or in a configuration in which the substrate is not facing the target.

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Li deficiencies in LiNbO3 films prepared by pulsed laser deposition in a buffer gas

Solid surface atoms are scattered backward by a bombardment of energetic particles such as accelerated ions. This phenomenon is called sputtering. The sputtering phenomena are used for the deposition of thin films. In this chapter, fundamentals of thin films are shortly reviewed for a better understanding of sputtering phenomena and/or sputtering deposition of thin films. Historically, thin films have been used for more than half a century in making electronic devices, optical coatings, instrument hard coatings, and decorative parts. The thin film processing is a well-established material processing technology. Thin films are fabricated by the deposition of material atoms on a substrate. A thin film is defined as a low-dimensional material created by condensing, one-by-one, atomic/molecular/ionic species of matter. The thickness is typically less than several micron-meters. The dimensions of thin films are the same range to nanomaterials. The thin film material technology is widely used for the nanomaterial processing. Thin film materials are in the same category as nanomaterials.

Thin Films and Nanomaterials

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.

C.S. Tsai

Papers

Integrated acoustooptic and magnetooptic devices for optical information processing