Polarization Diversity Coherent Receiver Research Articles

Simple polarization-insensitive coherent RoF link with increased capacity.

A simple polarization-insensitive coherent radio-over-fiber (RoF) link with increased spectrum efficiency and transmission capacity is proposed and demonstrated. Instead of using two polarization splitters (PBSs), two 90° hybrids, and four pairs of balanced photodetectors (PDs) in a conventional polarization-diversity coherent receiver (PDCR), a simplified PDCR with only one PBS, one optical coupler (OC), and two PDs is employed in the coherent RoF link. At the simplified receiver, a novel, to the best of our knowledge, digital signal processing (DSP) algorithm is proposed to achieve polarization-insensitive detection and demultiplexing of two spectrally overlapping microwave vector signals as well as the elimination of the joint phase noise originating from the transmitter and the local oscillator (LO) laser sources. An experiment is performed. The transmission and detection of two independent 16QAM microwave vector signals at identical microwave carrier frequencies of 3 GHz with a symbol rate of 0.5 GSym/s over a 25-km single-mode fiber (SMF) is demonstrated. Thanks to the spectrum superposition of the two microwave vector signals, the spectral efficiency as well as the data transmission capacity is increased.

Real-time dual-polarization transmission based on hybrid optical wireless communications

Abstract We present experimental work on a gigabit-capable and long-reach hybrid coherent UWDM-PON plus FSO system for supporting different applications over the same fiber infrastructure in the mobile backhaul (MBH) networks. Also, for the first time, we demonstrate a reconfigurable real-time DSP transmission/reception of DP-QPSK signals over standard single-mode fiber (SSMF) and FSO links. The receiver presented is based on a commercial field-programmable gate array (FPGA). The considered communication links are based on 20 UDWDM channels with 625 Mbaud and 2.5 GHz channel spacing. We are able to demonstrate the lowest sampling rate required for digital coherent PON by employing four 1.25 Gsa/s ADCs using an electrical front-end receiver that offers only 1 GHz analog bandwidth. We achieved this by implementing a phase and polarization diversity coherent receiver combined with the DP-QPSK modulation formats. The system performance is estimated in terms of receiver sensitivity. The results show the viability of coherent PON and flexible dual-polarization supported by software-defined transceivers for the MBH.

Coherent BOTDA Using Phase- and Polarization-Diversity Heterodyne Detection and Embedded Digital Signal Processing

We have proposed and experimentally demonstrated a configuration of coherent BOTDA using optical phase-and polarization-diversity heterodyne detection and embedded digital signal processing (DSP). With the unwanted probe sideband and Rayleigh scattered noise eliminated by stable electrical filtering, the in-phase and quadrature-phase heterodyne sensing signals in both x- and y-polarizations are received by the phase-and polarization-diversity coherent receiver with independent local light, and processed by the subsequent embedded DSP. The embedded DSP algorithms are designed to recover the baseband BOTDA trace for sensing and remove the intermediate frequency noise (both amplitude and phase noise) to avoid trace distortion. A spatial resolution of ~3 m and temperature accuracy of ±0.3 °C have been achieved over 40-km sensing distance. The configuration, compatible with the detection scheme of optical coherent communication systems, is potential for future high-speed coherent BOTDA with real-time DSP designed to satisfy different requirements.

Monolithic polarization diversity coherent receiver based on 120-degree optical hybrids on silicon

We present a monolithic polarization diversity coherent receiver by employing 120-degree optical hybrids on a silicon photonic integrated circuit (PIC). This PIC monolithically integrates silicon inverse tapers for fiber coupling, silicon polarization splitters, germanium high-speed photo detectors, and 120-degree optical hybrids based on 3x3 multimode interferometers (MMI). We demonstrate that 112-Gb/s polarization-division-multiplexed quadrature phase-shift keyed signals are detected in the wavelength range of 1530-1580 nm with comparable performance to commercial receivers.

Hybrid-Integrated Polarization Diverse Coherent Receiver Based on Polymer PLC

A dual-polarization coherent receiver using polymer planar lightwave circuit technology is demonstrated for the first time. It comprises optical 90 hybrids on the basis of polymer waveguides, polarization beam-splitting thin-film elements, and photodetectors made of InGaAsP/InP. The chip size fits into the existing receiver package standards. The receiver assembly shows a high polarization extinction ratio (>;25 dB over C-band) and is successfully operated in system experiments with 16-quadrature-amplitude modulation and quadrature phase-shift keying modulation up to 112 Gb/s.

Optical Performance Monitoring in Digital Coherent Receivers

In this paper, we present a method for combined fiber parameter estimation from digital filter coefficients of a polarization diverse coherent receiver. All deterministic linear optical channel parameters like residual chromatic dispersion (CD), polarization-mode dispersion (PMD), and polarization-dependent loss (PDL) are continuously monitored by analysis of the filter impulse response of the adaptive equalizer. After deriving the according equations from the theoretical linear fiber channel model, we demonstrate robust estimation for a joint combination of all impairments.

Channel Parameter Estimation for Polarization Diverse Coherent Receivers

A robust in-service estimation of fiber channel parameters from equalizer parameters of a polarization diverse coherent receiver is presented. The equations used for estimation are evolved from a theoretical fiber channel model. The theory is validated based on simulations and data from transmission experiments.

Electronic compensation of chromatic dispersion using a digital coherent receiver

Digital signal processing (DSP) combined with a phase and polarization diverse coherent receiver is a promising technology for future optical networks. Not only can the DSP be used to remove the need for dynamic polarization control, but also it may be utilized to compensate for nonlinear and linear transmission impairments. In this paper we present results of a 42.8Gbit/s nonlinear transmission experiment, using polarization multiplexed QPSK data at 10.7GBaud, with 4 bits per symbol. The digital coherent receiver allows 107,424 ps/nm of chromatic dispersion to be compensated digitally after transmission over 6400km of standard single mode fiber.

First heterodyne receiver frontend module including a polarization diversity receiver OEIC on InP

For the first time a packaged polarization diversity coherent receiver OEIC including detector units (photodetectors, JFET, load resistor) has been fabricated with the following data: waveguide loss 2 dB, 3 dB balance within 0.4 dB, polarization extinction >30 dB (TM) and >17 dB (TE), 3 dB cutoff frequency of 0.9 GHz, common mode rejection ratio 30 dB. >