ABSTRACT
We report on what is, to our knowledge, one of the first realizations of a CBC (coherent beam combining)-based laser emitter carrying a 10.66 Gb/s telecom signal in free-space optics, within the laboratory environment. Two telecom modulations have been tested: NRZ (non-return-to-zero, in amplitude) and DPSK (differential phase-shift keying, in phase). The modulated signal is split and amplified in three fiber amplifiers, delivering up to 3 W each. CBC of data amplified signals is achieved with residual phase errors well below < λ/60 RMS, using a phase-tagging technique (LOCSET). A first analysis of the influence of various parameters (such as phase-tagging modulation depth, optical path difference, number of channels, amplifier power) on the locking and data transmission quality is investigated. The study shows that the phase-tagging modulation depth and optical path difference are the main critical issues when carrying data on a CBC signal.
ABSTRACT
We realize a fiber Bragg grating InGaN-based laser diode emitting at 400 nm and demonstrate its high coherency. Thanks to the fabrication of a narrowband fiber Bragg grating in the near-UV, we can reach single-mode and single-frequency regimes for the self-injection locked diode. The device exhibits 44 dB side-mode suppression ratio and mW output power. Detailed frequency noise analysis reveals sub-MHz integrated linewidth and 16 kHz intrinsic linewidth. Such a narrow linewidth laser diode in the near-UV domain with a compact and low-cost design could find applications whenever coherency and interferometric resolutions are needed.
ABSTRACT
We theoretically and experimentally study the principle of phase-sensitive frequency conversion in a highly-nonlinear fiber using three pump waves. This mechanism, originally demonstrated with four continuous-wave pumps and a signal wave, is based on four-wave mixing and enables to convert the two quadrature components of the signal to different frequencies. In this work, we derive a set of two simple equations to describe this mechanism and find analytic solutions. We show that only three pumps are required, instead of four as originally proposed. We give simple relations to determine the initial conditions for the power levels and the phases of the pumps. To validate this approach, we perform an experimental demonstration of the three-pump scheme and find excellent agreement with the theory.
ABSTRACT
We report on all-optical wavelength conversion of a 56 Gb/s differential quadrature phase shift keying signal and a 42.7 Gb/s on-off keying signal. Wavelength conversion is based on four-wave mixing effect in a 1 m long highly nonlinear GeAsSe chalcogenide fiber. The high nonlinearity of the fiber allows low-power penalty operation with a total average power of less than 60 mW.
ABSTRACT
We report a chalcogenide suspended-core fiber with ultra-high nonlinearity and low attenuation loss. The glass composition is As(38)Se(62).With a core diameter as small as 1.13 µm, a record Kerr nonlinearity of 46,000 W(-1) km(-1) is demonstrated with attenuation loss of 0.9 dB/m. Four-wave mixing is experimented by using a 1m-long chalcogenide fiber for 10 GHz and 42.7 GHz signals. Four-wave mixing efficiencies of -5.6 dB at 10 GHz and -17.5 dB at 42.7 GHz are obtained. We also observed higher orders of four-wave mixing for both repetition rates.
ABSTRACT
Signal transmission experiments were performed at 170 Gbit/s in an integrated Al(2)O(3):Er(3+) waveguide amplifier to investigate its potential application in high-speed photonic integrated circuits. Net internal gain of up to 11 dB was measured for a continuous-wave 1532 nm signal under 1480 nm pumping, with a threshold pump power of 4 mW. A differential group delay of 2 ps between the TE and TM fundamental modes of the 5.7-cm-long amplifier was measured. When selecting a single polarization open eye diagrams and bit error rates equal to those of the transmission system without the amplifier were observed for a 1550 nm signal encoded with a 170 Gbit/s return-to-zero pseudo-random 2(7)-1 bit sequence.
ABSTRACT
We report on the experimental and theoretical study of a self-phase-modulation-based regenerator at 42.6 Gbit/s with a return-to-zero 33% format. We point out some detrimental effects such as intrachannel interactions and Brillouin scattering. An efficient solution, relying on a self-phase-modulation-based pulse compressor in combination with the regenerator, is proposed to overcome these detrimental phenomena. The experimental demonstration shows the effectiveness of a wavelength-transparent regenerator at 42.6 Gbit/s with a sensitivity-improvement of more than 5 dB and an eye-opening improvement of 2.3 dB in a back-to-back configuration, as well as a 10 times maximum transmission distance improvement for a BER of 10(-4).
Subject(s)
Filtration/instrumentation , Models, Theoretical , Optical Devices , Refractometry/instrumentation , Telecommunications/instrumentation , Computer Simulation , Computer-Aided Design , Equipment Design , Equipment Failure Analysis , Microwaves , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
We numerically investigate the 2R-regeneration technique utilizing self-phase modulation and off-center filtering. Our numerical simulations take into account the incoherent nature of noise through its spectral representation. This approach allows to evaluate a Q-factor improvement of 2 dB for this regenerator. Furthermore, our study points out the role of both the input and the output filter of this regenerator. We show that the input filter must be suitably chosen in order to obtain the best Q-factor improvement. The output filter must also be suitably chosen in order to preserve the modulation format.
