Photonic devices

This article focuses primarily on the properties of the most extensively studied III—V and II—VI compound semiconductors and is presented in five sections (/) a brief summary of the physical (mechanical and electrical) properties of the 2incblende cubic semiconductors (2) a description of the metal organic chemical vapor deposition (MOCVD) process. MOCVD is the preferred technology for the commercial growth of most heteroepitaxial semiconductor material (J) the physics and (4) apphcations of electronic and photonic devices and (5) the fabrication process technology in use to create both electronic and photonic devices and circuits. 

The relevance of photonics technology is best measured by its omnipresence. Semiconductor lasers, for example, are found in compact disk players, CD-ROM drives, and bar code scaimers, as well as in data communication systems such as telephone systems. Compound semiconductor-based LEDs utilized in multicolor displays, automobile indicators, and most recendy in traffic lights represent an even bigger market, with approximately 1 biUion in aimual sales. The trend to faster and smaller systems with lower power requirements and lower loss has led toward the development of optical communication and computing systems and thus rapid technological advancement in photonics systems is expected for the future. In this section, compound semiconductor photonics technology is reviewed with a focus on three primary photonic devices LEDs, laser diodes, and detectors. Overviews of other important compound semiconductor-based photonic devices can be found in References 75—78. 

There is a growing interest in the non-linear optical (NLO) properties of organic materials. Organic and polymeric materials with large non-linear optical coefficients can be used in principle in optoelectronic and photonic devices, and a great deal of research effort has been expended in efforts to design new compounds with optimal NLO properties. 

The substituted five-ring OPVs have been processed into poly crystal line thin films by vacuum deposition onto a substrate from the vapor phase. Optical absorption and photolumincscence of the films are significantly different from dilute solution spectra, which indicates that intermolecular interactions play an important role in the solid-state spectra. The molecular orientation and crystal domain size can be increased by thermal annealing of the films. This control of the microstruc-ture is essential for the use of such films in photonic devices. 

The lead compounds PbS, PbSe, PbTe are narrow-gap semiconductors that have been widely investigated for infrared detectors, diode lasers, and thermo-photovoltaic energy converters. Their photoconductive effect has been utilized in photoelectric cells, e.g., PbS in photographic exposure meters. Integrated photonic devices have been fabricated by their heteroepitaxial growth on Si or III-V semiconductors. 

A. D Andrea, A. Lapiccirella, G. Marietta and S. Viticoli (Eds.), Materials for Photonic Devices. World Scientific, Singapore (1991). 

Shyh Wang, Principles and Characteristics of Integratable Active and Passive Optical Devices Shlomo Margalit and Amnon Yariv, Integrated Electronic and Photonic Devices Takaaki Mukai, Yoshihisa Yamamoto, and Tatsuya Kimura, Optical Amplification by Semiconductor Lasers... 

T. Akutagawa, T. Hasegawa, T. Nakamura, in Handbook of Advanced Electronic and Photonic. Devices ed. H. S. Nalwa, Academic Press, San Diego, 2000, Vol. 3,267-301. 

The FPI principle can also be used to develop thin-film-coating-based chemical sensors. For example, a thin layer of zeolite film has been coated to a cleaved endface of a single-mode fiber to form a low-finesse FPI sensor for chemical detection. Zeolite presents a group of crystalline aluminosilicate materials with uniform subnanometer or nanometer scale pores. Traditionally, porous zeolite materials have been used as adsorbents, catalysts, and molecular sieves for molecular or ionic separation, electrode modification, and selectivity enhancement for chemical sensors. Recently, it has been revealed that zeolites possess a unique combination of chemical and optical properties. When properly integrated with a photonic device, these unique properties may be fully utilized to develop miniaturized optical chemical sensors with high sensitivity and potentially high selectivity for various in situ monitoring applications. 

We have shown that redox chromophores organized in LB films with resped to their orientation, alignment, or electronic interactions make very useful and specific photoresponses such as amplified fluorescence quenching, photocurrents controlled at the molecular level, photoinduced anisotropic eledrochromism, and photochemically modulated second harmonic generation. These results may contribute to facilitate the design and construction of novel photonic devices in the near future. 

G Yu, High performance photonic devices made with semiconducting polymers, Synth. Met., 80 143-150, 1996. 

Photonic Devices and Systems, edited by Robert G. Hunsberger... 

Nonlinear optical organic materials such as porphyrins, dyes, and phthalocyanines provide optical limiting properties for photonic devices to control light frequency and intensity in a predictable manner. The optical limit of CNTs composites is saturated at CNTs exceeding 3.8wt% relative to the polymer mass (Chen et al., 2002). Polymer/ CNT composites could also be used to protect human eyes, for example, optical elements, optical sensors, and optical switching (Cao et al., 2002). 

G. Guekos, ed., Photonic Devices for telecommunications how to model and measure, (Springer, Berlin, 1998). 

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