Important characteristics of optical detectors

Receiver sensitivity

                  The receiver sensitivity is the minimum amount of optical power level that can be received by the detector. If the sensitivity is high that detector can receive signals of having low strength and it reduces the bit error rate. The sensitivity is decided by the material used to manufacture the detector.

High fidelity

                  The detector must have the characteristic of receiving optical signal as it is. And detector should have the capability of generate the optical signal into electrical signal without destroying characteristic of the signal. Example - signal wave lengths frequency and phase.

Short response time

                  Short response time means the time taken by detector to receive optical signal generate the electrical signal. Better optical detector must have Short response time because the bandwidth is depending on the time of conversion. If the conversion time is high, we can get high bandwidth.

Small size

                  Detector must be compacted in size, in order to reduce the spare space it takes during the installation. But small size detectors are required high cost of manufacturing.

Minimum noise

                  Noise in the detector is caused due to photon to electrical conversion and the thermal noise in the detector. To detect the weakest signal, detector should maintain a high SNR. In order to do those detectors should have high quantum efficiency and low noises.

Linearity

                  Linearity is another important characteristic of optical detectors .Detectors are characterized by a response in which the output is linear with incident intensity. The response may be linear over a broad range, perhaps many orders of magnitude. If the output of the detector is plotted versus the input power, there should be no change in the slope of the curve.

Low cost

                  This is the most important factor when we selecting optical detector of our link. Most of detectors are highly cost because the technology and materials are very much expensive. If we can choose low cost detector our whole project will be successfully with low cost.