Optical Network Building Blocks- Semiconductor Optical Amplifiers

Semiconductor Optical Amplifier (SOA) is a device that can magnify an optical signal without changing it into an electrical signal. It has immense use in the optical communication network systems. SOAs are used as in-line amplifiers in optical communication as well as laser physics. A Semiconductor Optical Amplifier works like a laser diode but with a difference. The end mirrors of SOA have an anti-reflection coating or non-reflecting ends. This ensures that light is not dispersed and the optical signal is amplified resulting in a better quality of the signal. A good SOA can be used in fiber optic cables which have become the backbone of telecommunication network all over the world.

How does Semiconductor Optical Amplifier work?

A fiber optic amplifier works by amplifying optical signals directly, without first converting it into electrical signals. It also supports multi-channel operations across a wide bandwidth. Unlike other optical amplifiers, a 
Semiconductor Optical Amplifier uses a semiconductor to provide the amplification of wavelength across the distance. This is achieved by the anti-reflection design coating at both ends. SOAs are provided with stimulation (electric current) to amplify the optical signal.




What qualities should a good Semiconductor Optical Amplifier possess?
Optical communication networks hugely depend on optical amplifiers which can transmit signals over long distances without causing any loss. The parameters to be considered before purchasing a Semiconductor Optical Amplifier are:

·   Gain: highest gain appropriate to the usage

·   Gain bandwidth: wide optical bandwidth helps in amplifying a wide range of signal wavelengths

· Saturation output power: high saturation output power achieves good linearity, provides maximum range with minimum distortion

·   Noise figure: low noise figure reduces amplified spontaneous emission power at output

·  Polarization dependent gain: very low polarization sensitivity minimizes the gain difference between the 2 polarization states.
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Why is Semiconductor Optical Amplifier preferred over other amplifiers?
Since most of the world is driven by the internet, a good connection relies heavily on fiber optic cables. Semiconductor Optical Amplifier is hugely in demand for the same as they offer certain advantages over their contemporaries.

·   Small in size

·   Can be electrically pumped to amplify signal

·   Relatively less expensive than other optical amplifiers

·   Relatively less expensive than other optical amplifiers

·   All types of non-linear operations can be conducted using them

·   Can run with low power lasers


Though Semiconductor Optical Amplifier, has higher noise, lower gain, and moderate polarization dependence, it provides high-speed switching capabilities.

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