Performance Analysis of Mid-Wave Optical Receiver based on Barrier Upside-down nBn Photodetectors for Free Space Optical Wireless Communication Systems

Nowadays, Infrared Optical Detectors (IOD) play a very important role in the receivers of optical communication systems. The pin and APD photo-detectors are popular photo-detectors that act as receivers of optical signals. In this paper, we introduce a new structure called barrier upside-down nBn photo-detector (BU-nBn PD) for using in Free Space Optical Wireless Communication (FSOWC) systems which has a high capability. In the proposed structure, the absorber layer is selected from InAsSb (x
sb
=0.19) compound semiconductor, because it has a higher cutoff wavelength than the conventional commercially nBn photo-detectors with InAsSb (x
sb
=0.09). The simulation results indicate that the dark current of this photo-detector is 10
⁻¹⁰
A/cm
²
at 150K. Also, noise and signal-to-noise ratio (SNR) analysis are investigated which are two important and influencing factors in designing this device as a FSOWC receiver. In the proposed photo-detector, the noise and noise-equivalent-power (NEP) are 5.73×10
⁻¹³
(AHz
^−1/2
) and 6.24×10
⁻¹³
(WHz
^1/2
), respectively, at bias voltage of 0.5 V and 150 K.