By using appropriate self-similar scaling analysis, we delineate the generation of linearly chirped solitary pulses in photonic crystal fiber (PCF) at 850 nm to obtain the short pulses with large compression factor and minimal pedestal energy when compared to adiabatic compression scheme. The dispersion and nonlinearity varying nonlinear Schrdinger equation aptly models the pulse propagation in such a PCF. The analytical results demand that the effective dispersion must decrease exponentially while the nonlinearity must increase exponentially in the PCF. Thus, based on the analytical results, we propose the new design of tapered PCF by varying the pitch and diameter of the air hole. We adopt the projection operator method to derive the pulse parameter equations which indeed very clearly describe the self-similar pulse compression process at different parts of the PCF structures. As we are interested in constructing compact compressor, we also introduce another designing of PCF by filling chloroform in the core region. The chloroform filled tapered PCF exhibits low dispersion length for efficient pulse compression with low input pulse energy over small propagation distances. © 2010 IEEE.

Senthilnathan K

Department of Physics

School of Advanced Sciences

Vellore Campus

Raja R.V.J

Porsezian K

Nakkeeran K.

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Efficient Pulse Compression Using Tapered Photonic Crystal Fiber at 850 nm

IEEE Journal of Quantum Electronics

We propose a simple scheme to generate high-energy ultrashort pulses by combination and compression of multiple input pulses which share the same chirp profile. First, the multiple raised-cosine pulses in the input pulse train are modulated by a phase modulator, in which each modulation cycle covers two, three, four, or five pulses. Then, the modulated pulses are launched into a nonlinear fiber with the exponentially decreasing dispersion. We find that these pulses initially coalesce into a single pulse whose pulse profile is nearly hyperbolic secant, which then undergoes self-similar compression. Thus in the proposed method, first the combination of the multiple optical pulses occurs and then self-similar compression takes over. Besides, we also report the generation of ultrashort pulses by combination and compression of multiple hyperbolic secant pulses with the same chirp. The numerical results reveal that the resulting ultrashort pulse possesses a large portion of the input pulses for both raised-cosine and hyperbolic secant pulses. However, the compression factor and energy ratio are relatively higher for the hyperbolic secant pulses when compared with the raised-cosine pulses. © 1965-2012 IEEE.

Fulltext

Combination and Compression of Multiple Optical Pulses in Nonlinear Fibers with the Exponentially Decreasing Dispersion

We design various tapered photonic crystal fibers (PCFs) , namely, hexagonal tapered PCF (H-TPCF), octagonal tapered PCF (O-TPCF) and decagonal tapered PCF (D-TPCF) for generating self-similar ultrashort pulses (USPs) and stretched pulses . Here, we report on pulse compression as well as pulse stretching using the above mentioned PCFs wherein both dispersion and nonlinear profiles vary exponentially. Of these PCFs, we use dispersion decreasing PCFs for pulse compression process and dispersion increasing PCFs for pulse stretching process. From the detailed analysis, we find that H-TPCFs could generate high quality USPs with more compression percentage whereas D-TPCFs could produce high quality stretched pulses with more stretching percentage.

Springer Proceedings in Physics Recent Trends in Materials Science and Applications

A Comparative Study on Designing Efficient Pulse Compressors and Pulse Stretchers Using Tapered Photonic Crystal Fibers

We explore the optical properties of a proposed solid-core photonic quasi-crystal fiber (SC-PQF) of 10-fold for the wavelengths from 300 to 1100&nbsp;nm. The proposed SC-PQF exhibits a admissible low dispersion of −8.6481&nbsp;ps2/km, a third order dispersion of 0.00415&nbsp;ps3/km and a large nonlinearity of 1684&nbsp;W−1&nbsp;km−1 at 450&nbsp;nm, which turn out to be the desired optical properties for generating the few-cycle laser pulses. By exploiting these optical properties, we numerically demonstrate the generation of few-cycle laser pulses at 450&nbsp;nm wavelength by means of higher-order soliton effect compression.

Generation of Few-Cycle Laser Pulses Using A Photonic Quasi-crystal Fiber

In this paper, we propose a new type of optical waveguide called silicon nanowire embedded equai-angular spiral photonic crystal fiber (SN-SPCF) using fully vectorial finite element method, where closely arranged arrays of air holes act as cladding and nanosize silicon material at the centre acts as core. We show that the proposed nanowire embedded PCF of 400 nm core diameter exhibits high anomalous group velocity dispersion (-3148 ps2/km), small third order dispersion (-8.6591 ps3/km) and high nonlinearity (443.2 W-1m-1) at 1550 nm wavelength. Soliton-effect pulse compression of femtosecond pulses in a silicon nanowire-spiral photonic crystal fiber at 1550 nm is numerically studied. We demonstrate a pulse compression of 75 fs input pulse to about 4 fs by the simultaneous actions of both linear effects (a large anomalous group velocity dispersion and a small third order dispersion) and the nonlinear effect (an effective high nonlinearity).

Advanced Materials Research

Silicon Nanowire Embedded Spiral Photonic Crystal Fiber for Soliton-Effect Pulse Compression

We consider an optical pulse propagating in a tapered photonic crystal fiber (PCF) wherein dispersion as well as nonlinearity varies along the propagation direction. The generalized nonlinear Schrödinger equation aptly models the pulse propagation in such a PCF. The design of the tapered PCF is based on the analytical results, which demand that the dispersion decrease exponentially and the nonlinearity increase exponentially. In this paper, we adopt the generalized projection operator method for deriving the pulse-parameter equations of the Lagrangian variation method and the collective variable method. Besides, we consider another pulse profile called raised cosine (RC), which is aimed at replacing the conventional hyperbolic secant pulse. From the detailed results, we infer that the initial RC pulse evolves into a hyperbolic secant pulse. Further, in order to minimize the input power requirement, we employ the idea of replacing the solid core in the PCF with chloroform. In addition to the single pulse compression, we also investigate the possibility of multisoliton pulse compression. Here, we consider eight chirped hyperbolic secant pulses as input and generate a train of ultrashort pulses at 850 nm based on the chirped multisoliton pulse compression. In a similar way, we extend this pulse compression with eight RC pulses.

IEEE Photonics Journal

Generation of a Train of Ultrashort Pulses Near-Infrared Regime in a Tapered Photonic Crystal Fiber Using Raised-Cosine Pulses

Optik

Supercontinuum generation in chloroform-filled photonic crystal fibers

Applied Optics

Modeling the tapering effects of fabricated photonic crystal fibers and tailoring birefringence, dispersion, and supercontinuum generation properties

Journal of the Optical Society of America B

Nearly chirp- and pedestal-free pulse compression in nonlinear fiber Bragg gratings

Nature Photonics

Ten years of nonlinear optics in photonic crystal fibre

Physical Review A

Robust pedestal-free pulse compression in cubic-quintic nonlinear media

Journal	Data powered by TypesetIEEE Journal of Quantum Electronics
Publisher	Data powered by TypesetInstitute of Electrical and Electronics Engineers (IEEE)
ISSN	0018-9197
Open Access	No