08-16-2017, 09:15 PM
A photonic integrated circuit (PIC) or an integrated optical circuit is a device that integrates multiple (at least two) photonic functions and, as such, is similar to an electronic integrated circuit. The main difference between the two is that a photonic integrated circuit provides functions for information signals imposed at optical wavelengths typically in the visible or near infrared spectrum from 850 nm to 1650 nm.
The most commonly used material platform for photonic integrated circuits is indium phosphide, which allows the integration of various optically active and passive functions on the same chip. Initial examples of photonic integrated circuits were simple 2-section distributed Bragg reflector (DBR) lasers, consisting of two independently controlled device sections - a gain section and a DBR mirror section. Therefore, all modern lasers, monolithic tunable, widely tunable lasers, externally modulated lasers and transmitters, integrated receivers, etc. Are examples of photonic integrated circuits. Current state-of-the-art devices integrate hundreds of functions into a single chip. The pioneering work in this arena was done in Bell Labs. The most outstanding academic centers of excellence in photonic integrated circuits at InP are the University of California at Santa Barbara, USA, and the Technological University of Eindhoven in the Netherlands.
A 2005 development demonstrated that silicon can, although an indirect bandgap material, still be used to generate laser light through Raman nonlinearity. Said lasers are not electrically operated but optically driven and therefore still require an additional optical pump laser source. The primary application for photonic integrated circuits is in the area of fiber optic communication although applications in other fields such as biomedical computation and photonics are also possible.
The waveguide network (AWG) commonly used as optical multiplexers in wavelength division multiplexed (WDM) optical fiber communication systems is an example of a photonic integrated circuit that has replaced previous multiplexing schemes that used Multiple discrete filter elements. Since the separation of optical modes is a necessity for quantum computing, this technology may be useful for miniaturizing quantum computers (see linear optical quantum computation). Another example of a widely used integrated photon chip in fiber optic communication systems is the externally modulated (EML) laser that combines a distributed feedback laser diode with an electrodeposition modulator on a single chip based on InP.
