Tech Primer

Photonic Integrated Circuit

Photonic Integrated Circuit (PIC) or Integrated Optics is an optical data transmission device that integrates multiple photonic functions. This technology contains numerous optical components which are bonded together to fulfil complex functions. The chip is made up of indium phosphide, a semiconductor developed for its optical properties. The proposed chip would be light in weight in comparison to electric current.

Photonic chips generate, manipulate, and detect light rather than electrons. The technology of electronic integrated circuits has reflected numerous achievements such as complex, powerful microprocessors containing million transistors, specialised signal processors or computer memory chips with voluminous data storage capacity. It is expected that all major networking optical function like amplification, mux/demux, switching, transmitting or receiving will be performed by a single chip.

Optical Data Transmission equipments require lasers–to send light, multiplexers–to split and recombine modulators to encode data, and detectors that receive the data, low loss interconnect waveguides, and filters. Optical Data Transmission has higher data rates and at the same time eliminates problems resulting from electromagnetic interference. The implementation of silicon-based photonic devices will result in smaller and cheaper photonic devices.

Origin

Photonic Integrated Circuit is considered as a technology for next generation networks. In 2004, David Welch, cofounder of Infinera, an optical networks company, introduced a chip with 50 nanoscale optical components patterned into its surface named as Photonic Integrated Circuit. This is the fastest Optical Chip, 2 cm wide strip featuring four patterned gold-coloured rectangles, which contain a total of 240 patterned optical components. This chip developed by Infinera, 1.6 terabit version is considered as the fastest optical chip in the world and is expected to commercialise very soon. The 1.6 terabit version comprises of 40 lasers, 40 detectors, 40 modulators, 40 channels, and every modulator encodes data four times faster. The previously developed chips succeeded in integrating only a few devices on a single chip. The 100 gigabit version was the first device and was efficient to send and receive 100 gigabits of information per second. The 100 gigabit version comprised of 10 lasers, 10 detectors, 10 modulators that encode data by switching light on and off, and 10 waveguides that direct photons into a multiplexer.

Advantages and Disadvantages

PIC has brought forward cost and environmental advantages over circuits composed of discrete components. It allow optical systems to be made compact and perform better than discrete optical components. PIC has a possibility of integration with electronic circuits. Integrated components are reliable, power efficient and thus cut down operating costs. One of the obstacles of PIC is cost, since optical equipment is expensive. Other obstacles are space and time–due to speedy developments, life cycles of equipment are shrinking. Optical connections between waveguides and couplers are more critical than electrical connections. They exhibit optical losses, and to overcome this problem, an optical amplifier is required.

Vendors

Some of the vendors of Photonic Integrated Circuit are Agilent Technologies Inc., Agere Systems Inc., Alcatel Optronics, Bookham Technology PLC, Coring Inc. IBM Corp., JDS Uniphase Inc., etc.

For more information visit:
www.electronics.dit.ie/postdocs/qwang/Photonic%20Integrated%20Circuits.htm

—Garima Grover
grover_garima@hotmail.com