What is a Optical Receiver?

An optical receiver is a device that converts optical signals transmitted by optical fibers into electrical signals in communications.
This article provides a more comprehensive introduction to what is optical receiver and its components.
How optical receiver works with fiber optic, and how optical receiver works with optical transmitter.

What is optical receiver?

The optical receiver is one of the important devices in the optical fiber communication system.
The main function of the optical receiver is to receive the optical signal transmitted by the optical fiber and convert it into the electrical signal in communication.
The optical receiver can also perform associated signal processing or amplify the signal.
Optical receivers are mainly used in CATV systems, broadband access networks and large-scale optical fiber communication networks.

Why does an optical receiver consist of a photodetector and a transimpedance amplifier?
Optical receivers usually consist of photodetectors and transimpedance amplifiers. This has to do with how optical receivers work.
Photodetector

The photodeterctor is the main component of the optical receiver.
There are photodetectors made of many materials,
Silicon, for example, is the most commonly used material for making photodetectors.
Photoelectric ceramic materials, which have high density and high mechanical strength. They are often used in the manufacture of infrared photodetectors.
Semiconductor materials, photodetectors made of this material have high sensitivity and fast response.
The main function of photodetectors in optical receivers is to convert optical signals into electrical signals.
This process mainly relies on the photoelectric effect.

The basic steps for converting optical signals into electrical signals are:
1.Photon absorption
When light strikes the light-sensitive material of a photodetector, the photons interact with the atoms in the material.
2.Electronic excitation
After the photon is absorbed by the material, the electrons in the material jump from a low energy level to a high energy level.
3.Form electron-hole pairs
When an electron is excited into the conduction band, a hole is left where the electron originally was.
4.Carrier Migration
Under the action of the internal electric field of the photodetector, the excited electrons and holes move in opposite directions, forming an electric current.
This current caused by photogenerated carriers is called photocurrent.
5.Current Output
The photocurrent passes through the circuit structure of the photodetector, is amplified and conditioned. Then it is finally converted into a usable electrical signal output.
Transimpedance amplifier
Transimpedance amplifiers are also available in many materials. Such as semiconductors, silicon and insulating materials.
Insulating materials are often used to isolate different circuit parts.
Semiconductors and silicon are used to make semiconductor field-effect transistors (MOSFETs), a device commonly used in transimpedance amplifiers.
The transimpedance amplifier is located at the forefront of the optical receiver. It is an electronic amplifier.
The main function of the transimpedance amplifier is to convert the output current (signal) converted by the photodetector into a voltage signal. Then provides impedance matching during conversion.
The transimpedance amplifier provides the necessary electrical signal form for subsequent signal processing.
The process of converting output current into a voltage signal mainly relies on Ohm's law and negative feedback mechanisms.