Abstract:
With increasing IoT and a plethora of multimedia applications being used, there is an
ever-increasing demand for bandwidth-intensive applications coupled with costeffectiveness. Communication networks employing optical fiber had been the de facto
standard for such communication systems. The Optical Fiber network's high cost and
man-hours required for laying demand wireless solutions. Therefore, an optimum and
cost-effective duplex optical link for two channels baseband signal data transmission
has been designed and validated using a single laser source. The link is designed for
high data rate transmission between buildings within 1.5~2 km utilizing modular and
low complexity. An optical link for 20 Gb/sec duplex data transmission is designed
based upon single laser source utilization. A cost-efficient and simple design have been
accomplished with a transmission distance of 1.5 km by utilizing differential quadrature
phase shift keying (DQPSK) and On-Off Keying (OOK) modulation techniques. The
design allowed us to recycle the downlink signal in uplink transmission over free Space,
thus eradicating the requirement for a separate laser at the other end. Each channel's
transmission data rate was 10 Gb/sec. At the former end, the DQPSK technique was
employed for data modulation and the data was transmitted into free space. The data
was then split at the latter end for downlink reception along with reusing the downlink
received signal for uplink transmission to the former end utilizing the OOK modulation
technique. The received data was compared with the transmitted one to verify and
validate the system's accuracy through signal waveforms and BER (Bit Error Rate).
The eye diagrams and the Bit error rate (BER) graphs of the received downlink and
uplink signals over a duplex Free Space Optical (FSO) transmission link are discussed
and presented.
