Self-phase Modulation In Fiber Research Articles

OPTIMIZATION OF FEMTOSECOND PULSE COMPRESSION BY PULSE ASYMMETRY MANAGEMENT

We present results of numerical studies of the phase compensation in the pulse compression process via the shaping of asymmetric pulses at the system input. In this case, an effective pulse compression is achieved, with a ratio corresponding to the pulse spectral broadening in fiber. This opportunity is caused by the fact that self-phase modulation in fiber results in a phase given by the pulse shape.

Dispersion management optimization of multi-wavelength all-optical regeneration based on self-phase modulation

In connection with the multi-wavelength all-optical regeneration system based on self-phase modulation in fibers, the effect of the average fiber dispersion for the quality factor Q improvement of regenerator is analyzed and a dispersion management optimization method is proposed. The stability of performance of the regenerator will degrade because of dispersion discrepancy between different wavelengths. By choosing the fiber length of dispersion compensating fiber and single mode fiber to make the dispersion curve of combination of two kinds of fiber approximately fitting with the dispersion curve corresponding to the best performance of each wavelength respectively, and keeping the compound dispersion curve in the better dispersion region, the stability of performance of the regenerator is effectively improved if the input signal power and offset of the filter are properly adjusted. The optimization of multi-wavelength dispersion management can be realized.

Enhancement of Microwave Optical Link Gain by Self-Phase Modulation in a Fiber Interferometer

Self-phase modulation in optical fiber is used to enhance the radio-frequency gain of a microwave photonic link. Using the two outputs of a balanced Mach-Zehnder electrooptic modulator to feed two arms of a fiber interferometer, the modulation depth power is increased by over 8 dB across the frequency range 0.05-20.0 GHz. The measurements are predicted well by the theoretical model.

Optical regeneration using self-phase modulation and quasi-continuous filtering

We propose a scheme for 2R optical regeneration based on self-phase modulation in fiber and quasi-continuous filtering. Numerical simulations demonstrate the possibility of increasing the transmission reach from 3500 to more than 6000 km at 10 Gb/s using 100-km spans. Spectral broadening is shown to be small using this technique, indicating its suitability for wavelength-division-multiplexing regeneration

Two-bit all-optical analog-to-digital conversion by filtering broadened and split spectrum induced by soliton effect or self-phase modulation in fiber

The Kerr effect in fiber is expected to play a major role in ultrafast all-optical signal processing, which can overcome the obstacles of inherently limited operating speed of electronic devices. In this paper, we propose novel ultrafast and polarization-independent all-optical analog-to-digital conversion schemes. The proposed schemes are realized by filtering the broadened and split spectrum induced by the soliton effect or self-phase modulation in fiber with an arrayed waveguide grating. We conducted proof-of-principle experiments and successfully demonstrated two-bit all-optical analog-to-digital conversions with Gray code output, which shows the feasibility of the proposed scheme.

Time-Frequency (Wigner) Analysis of Linear and Nonlinear Pulse Propagation in Optical Fibers

Time-frequency analysis, and, in particular, Wigner analysis, is applied to the study of picosecond pulse propagation through optical fibers in both the linear and nonlinear regimes. The effects of first- and second-order group velocity dispersion (GVD) and self-phase modulation (SPM) are first analyzed separately. The phenomena resulting from the interplay between GVD and SPM in fibers (e.g., soliton formation or optical wave breaking) are also investigated in detail. Wigner analysis is demonstrated to be an extremely powerful tool for investigating pulse propagation dynamics in nonlinear dispersive systems (e.g., optical fibers), providing a clearer and deeper insight into the physical phenomena that determine the behavior of these systems.

Theoretical studies on optical fiber secure communication using chaotic phase encoding

In this paper, we present the synchronization of chaotic injected semiconductor lasers in an optical fiber system via phase-controllers controlling its lasing p hase shift, and a theoretical model for optical fiber chaotic secure communicati on system via chaos phase shift modulation by coupling a chaotic laser phase con trolled synchronization system and an optical fiber channel. Chaotic synchroniza tion is realized numerically under phase-controllers controlling in a long-haul optical fiber system. Optical fiber chaos propagation formula is demonstrated by analyzing theoretically the effect of optical fiber self-phase modulation on ch aotic signal and synchronization. Chaotic laser phase shift is controlled and it s signal is transmitted via continuous chaos shift keying modulation on end for optical fiber communication encoding. Chaotic laser demodulation is achieved via setting a phase shift of the receiver phase-controllers for optical fiber commu nication decoding. Application of chaotic digital encoding of 50Mbit/s rate is simulated numerically for long-haul optical fiber secure communication. The system parameter mismatch and robustness of anti-noise are analyzed numerically in long-haul optical fiber propagation, in particular.

Performance Analysis and Comparison of Optical 3R Regenerators Utilizing Self-Phase Modulation in Fibers

Performance of fiber-based optical signal regenerators consisting of a synchronous amplitude modulator, a highly nonlinear fiber, and an optical bandpass filter is analyzed. The regenerators are operated in two different schemes: one utilizes solitonlike pulse compression in anomalous-dispersion fiber and subsequent filtering, and the other utilizes spectrum broadening in normal-dispersion fiber and subsequent spectrum slicing. Regeneration performance is compared for the two schemes in terms of the shape of energy transfer function and abilities of noise and timing-jitter reduction. Although both types of regenerators show good regenerator performance, the one based on spectrum broadening and slicing has better ability to stabilize signal amplitude while requiring larger signal power launched into the nonlinear fiber. The effectiveness of the regenerators in single-channel quasi-linear highly dispersed pulse transmission and dispersion-managed soliton transmission is also numerically examined.

Optimization of Pulse Regeneration at 40 Gb/s Based on Spectral Filtering of Self-Phase Modulation in Fiber

Optimization of an all-optical 2R regenerator at 40 Gb/s that is based on self-phase modulation in fiber is presented. The effect of fiber length, launch power into the fiber, and regenerator filter offset on the regenerator performance are investigated. We show that all three parameters can be carefully chosen to maximize the pulse regeneration. When optimized, we demonstrate an improvement in Q value of 1.5 dB.

Transform-limited spectral compression due to self-phase modulation in fibers

We demonstrate near-transform-limited pulse generation through spectral compression arising from nonlinear propagation of negatively chirped pulses in optical fiber. The output pulse intensity and phase were quantified by use of second-harmonic generation frequency-resolved optical gating. Spectral compression from 8.4 to 2.4 nm was obtained. Furthermore, the phase of the spectrally compressed pulse was found to be constant over the spectral and temporal envelopes, which is indicative of a transform-limited pulse. Good agreement was found between the experimental results and numerical pulse-propagation studies.

THEORETICAL ANALYSIS OF FAST AND SLOW SATURABLE ABSORBER MODE LOCKING ERBIUM DOPED FIBER LASERS

This paper presents a theoretical model for erbium-doped fiber lasers, which are passively mode-locked by a semiconductor saturable waveguide acting as a slow saturable absorber and a nonlinear fast saturable absorber- The influences of semiconductor saturable waveguide, fiber self-phase modulation and self-amplitude modulation on mode-locking pulse width and chirp have been analyzed-

Limitations on peak pulse power, pulse width, and coding mask misalignment in a fiber-optic code-division multiple-access system

The authors analyze the effects of fiber dispersion and optical nonlinearity on a code-division multiple-access (CDMA) communications system. They assume that each transmitter has a unique phase-encoding mask to scramble the pulses, and that the intended receiver has the complementary phase-decoding mask to unscramble the pulses. The necessary nonlinear pulse propagation equation is derived using a new and systematic approach. The authors then determine the minimum allowable pulse width and the maximum pulse width for the system. They next calculate the maximum optical power, which is limited by the fiber's self-phase modulation. This power is significantly larger than the minimum detectable optical power determined by the noise in the electrical receiver, so that in practice any distortion caused by the fiber's optical nonlinearity can be avoided. From their calculations estimates for all important optical parameters are provided. The deleterious effect of a slight relative misalignment between the encoding and decoding masks is also investigated. >

Useful and detrimental aspects of self-phase modulation in fiber optical applications

Abstract This paper reviews the features of self-phase modulation (SPM) in single-mode optical fibers and discusses the useful and detrimental aspects of this fiber nonlinearity with respect to fiber optical transmission and device applications. After a short introduction to the physical origin of self-phase modulation in fibers the following topics will be addressed: transmission system limitations due to SPM, soliton propagation, optical pulse compression, modulational instability.

Compression of optical pulses chirped by self-phase modulation in fibers

The use of self-phase modulation in a single-mode fiber to chirp an optical pulse, which is then compressed with a grating-pair compressor, has been shown to be a practical technique for the production of optical pulses at least as short as 30 fsec. We report the results of a theoretical analysis of this process. Numerical results are presented for the achievable compression and compressed pulse quality as functions of fiber length and input pulse intensity. These results are given in normalized units such that they can be scaled to describe a wide variety of experimental situations and can be used to determine the optimum fiber length and compressor parameters for any given input pulse. Specific numerical examples are presented that suggest that the technique will generally be useful for input pulses shorter than about 100 psec. For energies of a few nanojoules per pulse, the compressed pulse widths will typically be in the femtosecond regime.