Experimental all-optical relay-assisted FSO link with regeneration and forward scheme for ultra-short pulse transmission

Abstract

This paper presents experimental results for an all-optical free-space optical (FSO) relay-assisted system by employing an all-optical regenerate and forward (AORF) scheme in order to increase the transmission link span. The ultra-short pulse (i.e., 2 ps) regeneration technique based on Mamyshev method is adopted. We have developed a dedicated experimental test-bed composed of optical fiber components and FSO links to demonstrate the proposed scheme and evaluate its performance in terms of the Q-factor and bit error rate (BER) under turbulence regimes for both single and dual-hop network architectures. We show that, using the AORF a hundred times improvement in the BER performance is achieved compared to the amplify-and-forward scheme for a fixed signal-to-noise ratio under turbulence conditions.

Relayed FSO Links for Ground-to-Train Communications

“…For optical regenerating relays a bandpass filter with 80 GHz followed by HNLF with an attenuation of 0.88 dB/km and length of 500 m is considered. The optical bandpass filter has a central wavelength of 1551 nm and a bandwidth of 3 nm [18]. For OEO regenerators Reed-Solomon FEC (RS(255,233)) is considered for its low latency, low complexity and low power consumption [21].…”

“…The spectral broadening is given by [18]: (16) where, is the initial bandwidth of the signal pulse, λ is the wavelength, and are the refractive index and the length of the HNLF, respectively and is the optical intensity of the pulse. Given that, the OBPF has a bandwidth of ω f and is shifted by Δω shift , the critical pulse intensity is given by [18]: (17) From (11), the extent of spectral broadening can be controlled and from (12), the minimum input pulse intensity can be calculated. Please note that, the SPM based 2R regenerator is compatible for the return to zero (RZ) modulation format and preferred due to its simple implementation.…”

Turbulence mitigation in a 28 GHz radio‐over‐free‐space optics link using an integrated Mach–Zehnder interferometer and a diversity combining receiver

“…Very recently, we proposed and experimentally demonstrated the use of Mamyshev regenerator for turbulence mitigation in a 10 Gb/s return‐to‐zero relay‐assisted DD‐based FSO transmission system [14]. We showed two orders of magnitude improvement in the bit error rate (BER) performance.…”

“…To compensate for the deterioration of signal quality due to turbulence, a number of techniques have been proposed including transmit and receive diversity combining (DC) [12], modulation and coding [13] and adaptive threshold detection [14], to name a few. Very recently, we proposed and experimentally demonstrated the use of Mamyshev regenerator for turbulence mitigation in a 10 Gb/s return-tozero (RZ) relay-assisted DD-based FSO transmission system [15]. We showed two orders of magnitude improvement in the bit error rate (BER) performance.…”

Diversity aided millimeter‐wave/free space optical cooperative relaying systems

“…[4][5][6] On the other hand, the salient features like cost effective, large bandwidth, quick, and easy deployment along with high-speed connection have encouraged researchers to utilize FSO systems as an alternate to existing wireless communication technologies such as radio frequency (RF) link. [7][8][9][10] FSO communication systems have been proposed for many applications such as backhaul for wireless cellular network, disaster recovery, and redundant link. 11 However, the signal is greatly prone to atmospheric factors including fog, rain, and smog that creates attenuation and thereby limit transmission link distance to few hundreds of meters.…”