Cross-phase Modulation In Fiber Research Articles

Wavelength conversion using fiber cross-phase modulation driven by two pump waves.

Wavelength conversion using all-optical phase modulation in a fiber driven by two pump waves is investigated. The operation features are analyzed using an all-optical phase modulation model with two parallel-/cross-polarized pump waves to generate a phase-preserving copy of the optical signal at an exact frequency up-/down-shifted by the two-pump detuning. The conversion efficiency is experimentally verified using a 300-m highly-nonlinear fiber. The results agree well with a theoretical prediction. The conversion bandwidth over 4 THz is achieved and error-free wavelength conversion for a 32-GBd polarization-division multiplexed 16QAM signal is demonstrated. The technique's applicability to a large-capacity wavelength-division multiplexed signals is also discussed.

All-Optical Data Frequency Multiplexing on Single-Wavelength Carrier Light by Sequentially Provided Cross-Phase Modulation in Fiber

A novel configuration for an all-optical bus-topology data-multiplexing system is proposed in which multichannel signals are sequentially multiplexed by frequency-division multiplexing (FDM) on a single-wavelength optical carrier by cross-phase modulation (XPM) in nonlinear fibers (NLFs) with subcarrier-modulated optical data signals. By using highly NLFs for XPM generators and providing amplitude-modulated subcarrier-multiplexed optical signals generated with directly modulated lasers or optical beat signals at multiple local connection points, we successfully demonstrate sequential all-optical FDM of data signals on a single-wavelength optical carrier followed by error-free data transmission through a standard fiber.

Multi-stage optical FDM of 12-channel 10-Gb/s data with 20-GHz exact channel spacing using fiber cross-phase modulation with optical subcarrier signals

A sequential optical frequency-division multiplexing technique using cross-phase modulation in fibers with exactly frequency-controlled optical subcarrier signals is proposed and demonstrated. 12 channels of 10-Gb/s ASK/DPSK signals with 20-GHz exact channel spacing are successfully multiplexed all-optically at 12 stages with 1-km intervals.

All-optical wavelength converter based on fiber cross-phase modulation and fiber Bragg grating

I present new method of phase modulation to amplitude modulation conversion (PM/AM conversion) that utilizes integrating capabilities of fiber Bragg grating (FBG). I found that the wavelength converter based on fiber cross-phase modulation (XPM) and new method of PM/AM conversion have an order of magnitude higher conversion efficiency then the wavelength converter based on sideband filtration method and up to 6 dB higher conversion efficiency then the converter based on the nonlinear optical loop mirror. Numerical analysis and experimental results are provided for bit rates up to 40 Gb/s.

High-Speed All-Optical First- and Second-Order Differentiators Based on Cross-Phase Modulation in Fibers

An ultrafast all-optical differentiator generating the first- and the second-order temporal derivative of the intensity of optical signals is presented in this paper. Differentiation is obtained via an optical fiber that plays the role of an optical phase modulator, an optical bandpass filter and a photodetector. The operation of the proposed device is theoretically studied in order to highlight significant parameters that affect the performance of the differentiator, namely the filter transfer function, the power of the propagating waves and the fiber characteristics (length and nonlinear coefficient). The comparison between the numerically calculated derivatives and the theoretically expected ones is performed by estimating the correlation coefficient between them. According to the numerical analysis, high correlation coefficients can be achieved in certain operating regimes. The same device can be utilized in order to produce ultrawideband (UWB) impulse signals. Electrical monocycle or doublet pulses can be obtained at the output of the photodetector (PD) using the proper tunable optical filter. Experimental verification of the theoretically predicted and numerically calculated results is finally presented for high bit-rate signals.

Experiments of all-optical switching due to cross-phase modulation in fiber grating coupler by lock-in amp. detection scheme

We report results of experiments examining cross-phase modulation effect on fiber grating coupler (FGC). All-optical switching are observed in both cases of high pump pulses emitted from high-power Nd:YAG laser and mode-locked EDF laser. Based on coherent detection using a lock-in amplifier, the red-shift of the Bragg wavelength for a FGC was estimated to be 0.04–0.06 nm/1.5–1.7 kW peak power of EDF pump light at 1.55 μm. To avoid mixture of pump pulse and signal light at 1.55 μm, we have also performed the experiment using high power Nd:YAG laser as a pump power. For a Nd:YAG laser, the red-shift of Bragg wavelength is estimated to be 0.06 nm at maximum pump power of 2.1 kW. A simple model for the proposed detection scheme is given and the resultant red-shift is analyzed numerically.

Numerical Investigation of a 160-Gb/s Reconfigurable Photonic Logic Gate Based on Cross-Phase Modulation in Fibers

A simple reconfigurable all-optical logic gate based on cross-phase modulation in highly nonlinear fibers is numerically demonstrated. Fine performance at 160 Gb/s is obtained for five logic functions (xor, or, nand, nor and not). The implementation simplicity and the high-bit-rate operation make the proposed device suitable for ultrafast applications in the emerging all-optical networks

Cross-phase modulation bandwidth in ultrafast fiber wavelength converters

We propose a novel analytical model for the characterization of fiber cross-phase modulation (XPM) in ultrafast all-optical fiber wavelength converters, operating at modulation frequencies higher than 1 THz. The model is used to compare the XPM frequency limitations of a conventional and a highly nonlinear dispersion shifted fiber (HN-DSF) and a bismuth oxide-based fiber, introducing the XPM bandwidth as a design parameter. It is shown that the HN-DSF presents the highest XPM bandwidth, above 1 THz, making it the most appropriate for ultrafast wavelength conversion.

Direct measurement of frequency and polarization dependences of cross-phase modulation in fibers from high-resolution optical spectra

We present the results of an experiment for frequency and polarization dependence characterization of non-linear cross-phase-modulation (XPM) effects in optical fibers. The measurement technique is based on the direct analysis of high-resolution optical spectra of a signal wave that is phase modulated by an intensity-modulated pump wave. Measurement results provide experimental confirmation of the scalar character, over the whole resonant frequency range, of the electrostrictive contribution to the nonlinear refractive index. Also, the results confirm experimentally the relation describing the polarization dependence of the Kerr contribution to XPM in non-polarization-maintaining fibers.

160 Gb/s variable length packet/10 Gb/s-label all-optical label switching with wavelength conversion and unicast/multicast operation

We report on the first demonstration of all-optical label switching (AOLS) with 160 Gb/s variable length packets and 10 Gb/s optical labels. This result demonstrates the transparency of AOLS techniques from previously demonstrated 2.5 Gb/s to this 160 Gb/s demonstration using a common routing and packet lookup framework. Packet forwarding/conversion, optical label erasure/re-write and signal regeneration at 160 Gb/s is achieved using a WDM Raman enhanced all-optical fiber cross-phase modulation wavelength converter. It is also experimentally shown that this technique enables packet unicast and multicast operation at 160 Gb/s. The packet bit-error-rate is measured for all optical label switched 16 /spl times/ 10 Gb/s channels and error free operation is demonstrated after both label swapping and packet forwarding.

All-optical demultiplexing using fiber cross-phase modulation (XPM) and optical filtering

All-optical demultiplexing of 80-Gb/s data to 10 Gb/s is demonstrated using spectral broadening-induced by cross-phase modulation (XPM) with subsequent optical band-pass filtering. Due to the time derivative effect of XPM, the control pulsewidth can be larger than the bit-slot of the incoming data, and still give a switch window suitable for demultiplexing. Operation at 10/sup -12/ bit-error rate is demonstrated. In principle, this approach will scale to extremely high bit rates due to the ultrafast fiber nonlinearities.