1,721,009 research outputs found
Phase regeneration of optical signals
No full textWe present recent advances in phase-sensitive amplification technology and its application to the regeneration of phase-encoded signals. Using a combination of parametric effects in fibers and optical injection locking of lasers, it is possible to observe phase regeneration in signals with multiple levels of phase encoding
Towards nonlinear conversion from mid- to near-infrared wavelengths using Silicon Germanium waveguides
Full text linkWe demonstrate the design, fabrication and characterization of a highly nonlinear graded-index SiGe waveguide for the conversion of mid-infrared signals to the near-infrared. Using phase-matched four-wave mixing, we report the conversion of a signal at 2.65 µm to 1.77 µm using a pump at 2.12 µm
Multilevel quantization of optical phase in a novel coherent parametric mixer architecture
No full textThe exponentially increasing capacity demand in information systems will be met by carefully exploiting the complementary strengths of electronics and optics. Optical signal processing provides simple but powerful pipeline functions that offer high speed, low power, low latency and a route to densely parallel execution. A number of functions such as modulation and sampling, complex filtering and Fourier transformation have already been demonstrated. However, the key functionality of all-optical quantization has still not been addressed effectively. Here, we report an all-optical signal processing architecture that enables, for the first time, multilevel all-optical quantization of phase-encoded optical signals. A four-wave mixing process is used to generate a comb of phase harmonics of the input signal, and a two-pump parametric process to coherently combine a selected harmonic with the input signal, realizing phase quantization. We experimentally demonstrate operation up to six levels
QPSK phase and amplitude regeneration at 56 Gbaud in a novel idler-free non-degenerate phase sensitive amplifier
No full textWe introduce a novel input-idler-free non-degenerate phase sensitive amplifier (PSA) configuration and use it for simultaneous phase and amplitude regeneration of quadrature phase shift keyed (QPSK) signals demonstrated at symbol rates up to 56 Gbaud
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Research Data for Polarization Insensitive Wavelength Conversion in a Dispersion-Engineered SiGe Waveguide
No full text</span
Polarization insensitive wavelength conversion in a low-birefringence SiGe waveguide
No full textWe report the first demonstration of a single-pass dual-orthogonal-pump FWM-based wavelength conversion scheme in a silicon-based waveguide. The silicon germanium (SiGe) waveguide used was designed to exhibit strong TE/TM mode similarity across a broad wavelength range as well as a large nonlinear coefficient . A polarization dependent loss (PDL) of just 0.42 dB was measured and the conversion of 40 Gb/s DPSK signals was demonstrated with 1.5 dB power penalty at a bit error ratio (BER) of 10-9
Optical properties of silicon germanium waveguides at telecommunication wavelengths
No full textWe present a systematic experimental study of the linear and nonlinear optical properties of silicon-germanium (SiGe) waveguides, conducted on samples of varying cross-sectional dimensions and Ge concentrations. The evolution of the various optical properties for waveguide widths in the range 0.3 to 2 µm and Ge concentrations varying between 10 and 30% is considered. Finally, we comment on the comparative performance of the waveguides, when they are considered for nonlinear applications at telecommunications wavelengths
All-optical phase regeneration with record PSA extinction ratio in a low-birefringence silicon germanium waveguide
Full text linkWe report a low-power continuous wave-pumped phase sensitive amplifier (PSA)-based phase regenerator implemented in a passive silicon-based waveguide. A polarization assisted-PSA, consisting of two orthogonally-polarized pumps and a phase-locked signal copolarized to one of them, was implemented in a low-birefringence silicon germanium (SiGe) waveguide. The strong TE/TM modal symmetry of the waveguide and its large nonlinear coefficient enabled the achievement of an extremely large phase sensitive extinction ratio of approximately 29 dB for a total input power of only 21.3 dBm. This SiGe-based PSA was used to demonstrate phase regeneration on a 20 Gb/s differential phase-shift keying signal, thereby reducing its error vector magnitude and phase error by three and six times respectively and enabling a bit-error ratio improvement of up to 2 dB
- …
