Phase discrimination and simultaneous frequency conversion of the orthogonal components of an optical signal by four-wave mixing in an SOA

Simultaneous conversion of the two orthogonal phase components of an optical input to different output frequencies has been demonstrated by simulation and experiment. A single stage of four-wave mixing between the input signal and four pumps derived from a frequency comb was employed. The nonlinear device was a semiconductor optical amplifier, which provided overall signal gain and sufficient contrast for phase sensitive signal processing. The decomposition of a quadrature phase-shift keyed signal into a pair of binary phase-shift keyed outputs at different frequencies was also demonstrated by simulation

Phase synchronization scheme for a practical phase sensitive amplifier of ASK-NRZ signals

We present a phase locking scheme that enables the demonstration of a practical dual pump degenerate phase sensitive amplifier for 10 Gbit/s non-return to zero amplitude shift keying signals. The scheme makes use of cascaded Mach Zehnder modulators for creating the pump frequencies as well as of injection locking for extracting the signal carrier and synchronizing the local lasers. An in depth optimization study has been performed, based on measured error rate performance, and the main degradation factors have been identified

Injection locking-based pump recovery for phase-sensitive amplified links

An injection locking-based pump recovery system for phase-sensitive amplified links, capable of handling 40 dB effective span loss, is demonstrated. Measurements with 10 GBd DQPSK signals show penalty-free recovery of a pump wave, phase modulated with two sinusoidal RF-tones at 0.1 GHz and 0.3 GHz, with 64 dB amplification. The operating power limit for the pump recovery system is experimentally investigated and is governed by the noise transfer and phase modulation transfer characteristics of the injection-locked laser. The corresponding link penalties are explained and quantified. This system enables, for the first time, WDM compatible phase-sensitive amplified links over significant lengths

Enhancing Four-Wave-Mixing Processes by Nanowire Arrays Coupled to a Gold Film

We consider the process of four-wave mixing in an array of gold nanowires strongly coupled to a gold film. Using full-wave simulations, we perform a quantitative comparison of the four-wave mixing efficiency associated with the thin film geometry with and without the nanowire arrays. When the nanowire array is present, both the delocalized surface plasmon of the film as well as the localized surface plasmon resonances of the nanowires contribute to the local field enhancement, yielding an overall FWM efficiency enhancement of up to four orders-of-magnitude over a wide range of excitation angles. The film-coupled nanowire array is easily amenable to nanofabrication, and could find application as an ultra-compact component for integrated photonic and quantum optic systems.Comment: 5 pages, 4 figure

Analysis of the Arabidopsis CDC2a Promoter (MOLECULAR BIOLOGY AND INFORMATION-Molecular Biology)

The eukaryotic cell division cycle is tightly controlled by a class of protein kinases. Arabidopsis CDC2a has been considered to encode one of those protein kinases because it is expressed in proliferating tissues and can complement defects in the cdc2 gene of Schizosaccharomyces pombe. The promoter of CDC2a was investigated as a first step in exploring the regulation of plant cell proliferation. We found that its transcription is started at the position 677-base-pairs upstream from the CDC2a initiation codon. To localize the cis-element for proliferating-cell-specific expression, histochemical analysis was done with b- glucuronidase fusion genes containing various upstream regions of CDC2a. Results from the experiment indicated that a region downstream from the transcription start site is required for the proliferating-cellspecific expression of CDC2a and that an upstream region contains a cis-element directing transcription during trichome development