The photonic integrated circuit (also known as PIC) is a complex integrated circuit that incorporates a large number of optical devices to form a single photonic circuit. The main difference between a PIC and an electronic IC is that the PIC is analogous to an integrated electronic circuit. Many optical devices such as optical amplifiers, multiplexers, de-multiplexers, optical lasers, attenuators and also detectors are integrated into a photonic integrated circuit. For a large-scale operation of such a device, thousands of optical devices will be integrated into the device.
In a PIC, the signals are sent overlapping them in wavelengths generally in the range between the visible and infrared spectrum. The range is usually between 800 nanometers and 1700 nanometers.
In 2005, during a development of a laser light through the silicon in an electronic integrated circuit, there was a problem with the quantum noise, that prevented the generation. This problem was easily overcome by a photonic integrated circuit, which easily created the laser light and also in a higher bandwidth, within the circuit as a single medium. Therefore, the importance of PIC was known.