Abstract
A statistical model linking the probability of detecting photons in a photon counting experiment to the average number of input photons is used to analytically derive an error distribution of the estimates of the average number of photons in coherent input pulses. The estimates distribution determines the required number of experimental count runs required for an acceptable measurement error, for any value of the average number of input photons. An expression for the minimum detectable power by photon counting is obtained, fully capturing the effect of the photon counting statistics thereby completing an earlier analysis.

Abstract
We show experimental results of clock recovery from return-to-zero (RZ) format data by using injection locking of a free-running optoelectronic oscillator (OEO) circuit, which consists of a resonant tunneling diode (RTD) oscillator integrated circuit with both a detector and optical source. Error free extraction of a clock signal from the RTD-OEO is shown under both optical and electrical injection. The clock recovery performance at similar to 1.25 Gb/s is analyzed in terms of timing jitter, phase noise and locking bandwidth.

Abstract
The digital equalization of fibre impairments in coherent optical communications allows for ultimate limits of spectral efficiency to be achieved, while reducing the cost and complexity compared to optical based solutions. Digital backpropagation (BP) was proposed recently as a reduced complexity approach for jointly compensating linear and non-linear impairments in single polarization coherent optical systems. Furthermore, polarization division multiplexed quadrature phase-shift keying (PDM-QPSK) has emerged as a promising format to increase spectral efficiency. Here we assess the performance of the simplified backpropagation equalization in both single channel and multiple channel transmission in combination with polarization multiplexing for different dispersion map configurations. It is shown that polarization multiplexing induces a degradation in performance due to cross-phase modulation polarization scattering, the backpropagation algorithm still overperforming linear equalization.

Abstract
In this paper, we study the performance of OFDM signals in frequency-interleaved WDM radio-over-fiber (RoF) links with optical channel selection made by a uniform Fiber Bragg grating (FBG). The frequency-interleaved signals, transported over 10 km of standard single mode fiber, were transmitted in optical double-sideband (ODSB) format and filtered in optical single-sideband (OSSB) format. The simulations were being performed using the software VPI and the system performance was evaluated in terms of Error Vector Magnitude (EVM). The EVM is kept below 10% in the 100 and 400 Mbits/s for some optical power values and the system performance is limited by the dispersion in the FBG and nonlinearities in the optical modulator.

Abstract
The versatile transceiver in study for the Super Large Hadron Collider (SLHC) will have to endure severe radiation and temperature conditions while providing a high speed digital communication link to cover the experiment requirements. For this, characterization and model analysis of the electro-optic components (in particular the semiconductor laser), is of utmost importance as it will enable the correct design and optimization of the transceiver. It will also enable the prediction of the impact on the link performance when the physical characteristics of the device are changed due to the environmental circumstances. A measurement methodology is presented that leads to the conception of a model implemented in Verilog-A, for designing a robust system capable of complying with the demanding requirements of the experiment. The theoretical model shows a good agreement with the experimental data. This model was created based on a Vertical Cavity Surface Emitting Laser (VCSEL), but can be applied to a variety of lasers.

Abstract
We propose the use of inverse scattering on the design of ultra wide band nonuniform coupled line directional couplers with a specified coupling response. The inverse scattering is performed using the layer peeling algorithm which is simple and of easy implementation as a computer routine. To validate the method a wide band directional coupler is designed and implemented. © 2012 IEEE.