Integrated 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. 

It is well known that high-quality three-dimensional photonic stmctures, e.g., buried chaimel waveguides, which can be used for laser emissions, have been readily created on transparent laser ceramics, by using irradiations of short-pulse lasers [263-271] and particle beams [272—278]. This process is based on the controlled modification of the refractive index of the electronic processes and thermally induced transformations associated with laser irradiation. Laser writing to create such structures is a one-step process without the requirement of special preparation. It is a very fast, highly reproductive, and thus low-cost process. It has been employed to fabricate various integrated photonic devices. 

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... 

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. 

A. Sudbo and P.I. Jensen, Stable bidirectional eigenmode propagation of optical fields in waveguide devices, Integrated Photonics Research, 27-29 (OSA, Monterey, 1995). 

S. Margalit and A. Yariv, Integrated Electronic and Photonic Devices... 

All of the applications involving waveguides discussed in the previous section may be considered passive . The polymer serves some structural, protective, or guiding function but is not integral to the functioning of a device. A number of photonic device applications are available, however, where polymers may be useful as active elements. These applications require some type of nonlinear optical response when the material is irradiated with light of very high intensity, usually from a laser. 

Measurements at low light levels are routinely performed with photon-counting techniques. The development of ultrasensitive optical detectors has made great progress in the last couple of years. Integrated photon-counting modules with cooled avalanche photodiodes (APD) have been available for some years [31]. These detectors can have quantum efficiencies of 50% with less than 10 dark counts per second. The light sensitive area of such a device has a diameter of about 200 (im and can serve directly as a pinhole in a confocal detection channel. 

Input and output terminals are used to connect the nanophotonic device in the integrated circuit with external macroscopic photonic devices. The input terminal is used to convert the incident propagating light (free photons) to the optical near-held... 

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