Optical Communications|5 Article(s)
Visible light communications: 3.75 Mbits/s data rate with a 160 kHz bandwidth organic photodetector and artificial neural network equalization [Invited]
Zabih Ghassemlooy, Paul Anthony Haigh, Francesco Arca, Sandro Francesco Tedde, Oliver Hayden, Ioannis Papakonstantinou, and Sujan Rajbhandari
This paper presents an experimental demonstration of a visible light communications link with an light emitting diode and a low-bandwidth organic photodetector as transmitter and receiver, respectively, that achieves sub 4 Mbits/s speeds. An artificial neural network (ANN) equalizer is required in order to achieve such high data rates because of the influence of intersymbol interference. The digital modulation formats tested in this paper are nonreturn-to-zero on–off keying (OOK), and fourth-order pulse position modulation (4-PPM). Without equalization, data rates of 200 and 300 kbits/s can be achieved for 4-PPM and OOK, respectively. With ANN equalization, data rates of 2.8 and 3.75 Mbits/s can be achieved for the first time for OOK and 4-PPM, respectively.
Photonics Research
  • Publication Date: Jul. 19, 2013
  • Vol. 1, Issue 2, 02000065 (2013)
SIMO detection schemes for underwater optical wireless communication under turbulence
Weihao Liu, Zhengyuan Xu, and Liuqing Yang
In underwater optical wireless communication (UOWC), a channel is characterized by abundant scattering/absorption effects and optical turbulence. Most previous studies on UOWC have been limited to scattering/absorption effects. However, experiments in the literature indicate that underwater optical turbulence (UOT) can cause severe degradation of UOWC performance. In this paper, we characterize an UOWC channel with both scattering/absorption and UOT taken into consideration, and a spatial diversity receiver scheme, say a single-input–multiple-output (SIMO) scheme, based on a light-emitting-diode (LED) source and multiple detectors is proposed to mitigate deep fading. The Monte Carlo based statistical simulation method is introduced to evaluate the bit-error-rate performance of the system. It is shown that spatial diversity can effectively reduce channel fading and remarkably extend communication range.
Photonics Research
  • Publication Date: Apr. 06, 2015
  • Vol. 3, Issue 3, 03000048 (2015)
All-optical regeneration of polarization of a 40 Gbit/s return-to-zero telecommunication signal [Invited]
J. Fatome, D. Sugny, S. Pitois, P. Morin, M. Guasoni, A. Picozzi, H. R. Jauslin, C. Finot, G. Millot, and S. Wabnitz
We report all-optical regeneration of the state of polarization of a 40 Gbit/s return-to-zero telecommunication signal. The device discussed here consists of a 6.2-km-long nonzero dispersion-shifted fiber, with low polarization mode dispersion, pumped from the output end by a backward propagating wave coming from either an external continuous source or a reflection of the signal. An initially scrambled signal acquires a degree of polarization close to 100% toward the polarization generator output. All-optical regeneration is confirmed by means of polarization and bit-error-rate measurements as well as real-time observation of the eye diagrams. We show that the physical mechanism underlying the observed four-wave-mixing-based polarization attraction phenomenon can be described in terms of the geometric approach developed for the study of Hamiltonian singularities.
Photonics Research
  • Publication Date: Jul. 17, 2013
  • Vol. 1, Issue 3, 03000115 (2013)
Scalable nonlinear equalization in high-bit-rate optical transmission systems
Rameez Asif, Humayun Shahid, Farzana Arshad, and and Rashid Saleem
In this paper, we report on the performance comparison of all-optical signal processing methodologies to compensate fiber transmission impairments, namely chromatic dispersion and nonlinear distortion caused by the Kerr effect, in a coherent 112 Gbit∕s dual-polarization 64 bit quadrature amplitude modulation system over 800 km standard single-mode fiber. We numerically compare optical backward propagation (OBP) with optical phase conjugation (OPC) techniques, namely. mid-link spectral inversion, predispersed spectral inversion, and OPC with nonlinearity module. We also evaluate a self-phase-modulation-based optical limiter with an appropriate prechirping to compensate for the intensity fluctuations as a hybrid approach with OBP. The results depict improvement in system performance by a factor of ~4 dB of signal input power by all-optical signal processing methods, which is comparative with ideal digital backward propagation where the high complexity is the intrinsic impediment in the real-time implementation of the technique with coherent receivers.
Photonics Research
  • Publication Date: Sep. 15, 2013
  • Vol. 1, Issue 3, 03000130 (2013)