Photonic integrated circuit
Encyclopedia
A photonic integrated circuit (PIC) or integrated optical circuit is a device that integrates multiple photonic functions and as such is analogous to an electronic integrated circuit
. The major difference between the two is that a photonic integrated circuit provides functionality for information signals imposed on optical wavelengths typically in the visible spectrum
or near infrared
850 nm-1650 nm.
A 2005 development solved a quantum noise
problem that prevented silicon
from being used to generate laser
light, permitting new integrated circuits to use high-bandwidth
laser light generated within the circuit itself as a signal medium.
is the dominant material, system photonic integrated circuits have been fabricated from a variety of material systems, including electro-optic crystals such as lithium niobate
, silica on silicon, Silicon on insulator
, various polymers and semiconductor
materials which are used to make semiconductor lasers such as GaAs
and InP. The different material systems are used because they each provide different advantages and limitations depending on the function to be integrated.
The fabrication techniques are similar to those used in electronic integrated circuits in which photolithography
is used to pattern wafers for etching and material deposition. Unlike electronics where the primary device is the transistor
, there is no single dominant device. The range of devices required on a chip includes low loss interconnect waveguides, power splitters, optical amplifiers, optical modulators, filters, lasers and detectors. These devices require a variety of different materials and fabrication techniques making it difficult to realize all of them on a single chip.
Newer techniques using resonant photonic interferometry is making way for UV LEDs to be used for optical computing requirements with much cheaper costs leading the way to PHz consumer electronics.
though applications in other fields such as biomedical and photonic computing
are also possible.
The arrayed waveguide grating
(AWG) which are commonly used as optical (de)multiplexers in wavelength division multiplexed (WDM) fiber-optic communication
systems are an example of a photonic integrated circuit which has replaced previous multiplexing schemes which utilized multiple discrete filter elements.
Another example of a photonic integrated chip in wide use today in fiber-optic communication
systems is the externally modulated laser (EML) which combines a distributed feed back laser diode
with an electro-absorption modulator
on a single InP based chip.
Photonic integrated circuits should also be immune to the hazards of functionality losses associated with electromagnetic pulse
(EMP), though may not be immune to high neutron flux
.
Also, it is part of recommendations by the Optical Internetworking Forum
for inclusion in 100 gigahertz optical networking standards:
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
. The major difference between the two is that a photonic integrated circuit provides functionality for information signals imposed on optical wavelengths typically in the visible spectrum
Visible spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm. In terms of...
or near infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
850 nm-1650 nm.
A 2005 development solved a quantum noise
Quantum noise
Quantum noise is uncertainty of some physical quantity due to its quantum origin.In the case of number of particles , the quantum noise is also called shot noise. Most optical communications use amplitude modulation...
problem that prevented silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
from being used to generate laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
light, permitting new integrated circuits to use high-bandwidth
Bandwidth (computing)
In computer networking and computer science, bandwidth, network bandwidth, data bandwidth, or digital bandwidth is a measure of available or consumed data communication resources expressed in bits/second or multiples of it .Note that in textbooks on wireless communications, modem data transmission,...
laser light generated within the circuit itself as a signal medium.
Comparison to electronic integration
Unlike electronic integration where siliconSilicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
is the dominant material, system photonic integrated circuits have been fabricated from a variety of material systems, including electro-optic crystals such as lithium niobate
Lithium niobate
Lithium niobate is a compound of niobium, lithium, and oxygen. Its single crystals are an important material for optical waveguides, mobile phones, optical modulators and various other linear and non-linear optical applications.-Properties:...
, silica on silicon, Silicon on insulator
Silicon on insulator
Silicon on insulator technology refers to the use of a layered silicon-insulator-silicon substrate in place of conventional silicon substrates in semiconductor manufacturing, especially microelectronics, to reduce parasitic device capacitance and thereby improving performance...
, various polymers and semiconductor
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
materials which are used to make semiconductor lasers such as GaAs
Gaas
Gaas is a commune in the Landes department in Aquitaine in south-western France....
and InP. The different material systems are used because they each provide different advantages and limitations depending on the function to be integrated.
The fabrication techniques are similar to those used in electronic integrated circuits in which photolithography
Photolithography
Photolithography is a process used in microfabrication to selectively remove parts of a thin film or the bulk of a substrate. It uses light to transfer a geometric pattern from a photomask to a light-sensitive chemical "photoresist", or simply "resist," on the substrate...
is used to pattern wafers for etching and material deposition. Unlike electronics where the primary device is the transistor
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
, there is no single dominant device. The range of devices required on a chip includes low loss interconnect waveguides, power splitters, optical amplifiers, optical modulators, filters, lasers and detectors. These devices require a variety of different materials and fabrication techniques making it difficult to realize all of them on a single chip.
Newer techniques using resonant photonic interferometry is making way for UV LEDs to be used for optical computing requirements with much cheaper costs leading the way to PHz consumer electronics.
Examples of photonic integrated circuits
The primary application for photonic integrated circuits is in the area of fiber-optic communicationFiber-optic communication
Fiber-optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry information...
though applications in other fields such as biomedical and photonic computing
Photonic computing
Today's computers use the movement of electrons in-and-out of transistors to do logic. Optical or Photonic computing is intended to use photons or light particles, produced by lasers or diodes, in place of electrons...
are also possible.
The arrayed waveguide grating
Arrayed waveguide grating
Arrayed waveguide gratings are commonly used as optical multiplexers in wavelength division multiplexed systems. These devices are capable of multiplexing a large number of wavelengths into a single optical fiber, thereby increasing the transmission capacity of optical networks considerably.The...
(AWG) which are commonly used as optical (de)multiplexers in wavelength division multiplexed (WDM) fiber-optic communication
Fiber-optic communication
Fiber-optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry information...
systems are an example of a photonic integrated circuit which has replaced previous multiplexing schemes which utilized multiple discrete filter elements.
Another example of a photonic integrated chip in wide use today in fiber-optic communication
Fiber-optic communication
Fiber-optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry information...
systems is the externally modulated laser (EML) which combines a distributed feed back laser diode
Distributed feedback laser
A distributed feedback laser is a type of laser diode, quantum cascade laser or optical fibre laser where the active region of the device is periodically structured as a diffraction grating...
with an electro-absorption modulator
Electro-absorption modulator
Electro-absorption modulator is a semiconductor device which can be used for modulating the intensity of a laser beam via an electric voltage...
on a single InP based chip.
Advantages of photonic circuits
Photonic integrated circuits can allow optical systems to be made more compact and higher performance than with discrete optical components. They also offer the possibility of integration with electronic circuits to provide increased functionality.Photonic integrated circuits should also be immune to the hazards of functionality losses associated with electromagnetic pulse
Electromagnetic pulse
An electromagnetic pulse is a burst of electromagnetic radiation. The abrupt pulse of electromagnetic radiation usually results from certain types of high energy explosions, especially a nuclear explosion, or from a suddenly fluctuating magnetic field...
(EMP), though may not be immune to high neutron flux
Neutron flux
The neutron flux is a quantity used in reactor physics corresponding to the total length travelled by all neutrons per unit time and volume . The neutron fluence is defined as the neutron flux integrated over a certain time period....
.
Current status
Photonic integration is currently an active topic in U.S. Defense contracts:- https://www.fbo.gov/index?s=opportunity&mode=form&id=fd9392a50a171edce2320a343a203285&tab=core&_cview=1
- https://www.fbo.gov/index?s=opportunity&mode=form&id=9a3f9e7d9a5b20626be43d93bfacb2a6&tab=core&_cview=0
Also, it is part of recommendations by the Optical Internetworking Forum
Optical Internetworking Forum
The Optical Internetworking Forum is a non-profit, member-driven organization founded in 1998. It promotes the development and deployment of interoperable networking solutions and services through the creation of Implementation Agreements for optical networking products, network processing...
for inclusion in 100 gigahertz optical networking standards:
- http://www.oiforum.com/public/documents/OIF_CEI-28G_WP_Final.pdf