Victor E. Perlin

Generation of narrow-band terahertz radiation via optical rectification of femtosecond pulses in periodically poled lithium niobate

We demonstrate a promising technique for generating narrow-band terahertz electromagnetic radiation. Femtosecond optical pulses are propagated through a periodically poled lithium-niobate crystal, where the domain length is matched to the walk-off length between the optical and THz pulses. The bandwidth of the THz wave forms is 0.11 at 1.7 THz. Optical rectification gives rise to a THz wave form which corresponds to the domain structure of the periodically poled lithium niobate.

Optimal design of flat-gain wide-band fiber Raman amplifiers

We present a novel method for designing multiwavelength pumped fiber Raman amplifiers with optimal gain-flatness and gain-bandwidth performance. We show that by solving the inverse amplifier design problem, relative gain flatness well below 1% can be achieved over bandwidths of up to 12 THz without any gain equalization devices. This constitutes a substantial improvement in gain flatness compared to the existing wide-band optical fiber amplifiers.

On distributed Raman amplification for ultrabroad-band long-haul WDM systems

We present an analysis and design method for multiwavelength pumped fiber Raman amplifiers for massive wavelength division multiplexing (WDM) systems with signal bandwidths of 10 to 12 THz and a very large number of channels. We solve self-consistently the optimal design problem for backward-pumped distributed Raman amplifiers with special gain profiles that compensate for the Raman tilt and wavelength-dependent fiber loss. We study the noise performance of these optimally designed amplifiers and address the issues of multispan amplification for long-haul transmission of such broadband signals.

Distributed feedback fiber Raman laser

We analyze the properties of a distributed feedback fiber laser based on Raman amplification. Such a laser is quite practical and has a number of novel properties. We model numerically the laser dynamics, analyze in detail the role of the nonlinear refractive index of the fiber and argue on the optimal design parameters.

Optimizing the noise performance of broad-band WDM systems with distributed Raman amplification

We derive the fundamental limit for the ratio of path-averaged signal power to optical signal-to-noise ratio (OSNR), and show that for a fixed nonlinear weight, the OSNR is maximized if the signal power variation along the fiber is minimal. We also derive the conditions under which the noise performance of Raman amplification can be improved by erbium-doped fiber amplifier post amplification.

Nonlinear pulse switching using long-period fiber gratings

We show that the intensity required to achieve all-optical switching in long-period fiber gratings can be reduced by orders of magnitude through the use of uniform phase-shifting regions between gratings. Predicted switching intensities are of the order 100 MW/cm/sup 2/ compared to 10 GW/cm/sup 2/ for normal device configuration.

On trade-off between noise and nonlinearity in WDM systems with distributed Raman amplification

We have analyzed the fundamental limits for the ratio of OSNR and the nonlinear weight in WDM systems with distributed Raman amplification. This limit is approached when the signal power variation along the fiber, signal-to-signal Raman scattering, and temperature dependent noise are minimized, and EDFA post-amplification is not used.

Nonlinear pulse switching using cross-phase modulation and fiber Bragg gratings

We propose and analyze a new all-optical nonlinear switch. The device is based on cross-phase modulation (XPM)-induced temporary frequency shift upon co-propagation of signal and control pulses with walkoff, and on the filtering effect of a fiber Bragg grating (FBG). Very high ON/OFF contrast with practically no pulse distortion can be achieved with moderate switching power. The new device possesses some important advantages over nonlinear optical-loop mirror switches.

All-fiber wavelength conversion using cross-phase modulation and Bragg gratings

In this letter, we show that by using the frequency shift induced by cross-phase modulation and the filtering action of fiber Bragg gratings (FBGs) simple, efficient, and universal wavelength converters can be implemented. With the appropriately synthesized FBGs, the converted pulses can have exactly the same shape and spectrum as the input signal pulses for any values of walkoff and dispersion present in the system. Conversion over wide wavelength ranges can be achieved, and the bit rate is limited only by the required input signal power.

Efficient design method for multi-pump flat-gain fiber Raman amplifiers

There is much current interest in fiber Raman amplifiers pumped at multiple wavelengths (MW-FRA), which can combine the low-noise advantage of distributed Raman amplification with the possibility of ultra-wide (80 nm and above) gain bandwidths.