Partha Sona Maji

A New Design for All-Normal Near Zero Dispersion Photonic Crystal Fiber with Selective Liquid Infiltration for Broadband Supercontinuum Generation at 1.55 μm

A new design of all-normal and near zero flattened dispersion based on all-silica photonic crystal fibers (PCFs) using selectively liquid infiltration technique has been proposed to realize smooth broadband supercontinuum generation (SCG). The investigation gives the details of the effect of different geometrical parameters along with the infiltrating liquids on the dispersion characteristics of the fiber. Numerical investigations establish a dispersion value of −0.48 ps/nm/km around the wavelength of 1.55 μm. The optimized design has been found to be suitable for SCG around the C band of wavelength with flat broadband wavelength band (375 nm bandwidth) and smooth spectrum with only a meter long of the PCF. The proposed structure also demonstrates good tunable properties that can help correct possible fabrication mismatch towards a better optimization design for various optical communication systems.

Circular Photonic Crystal Fibers: Numerical Analysis of Chromatic Dispersion and Losses

Detailed numerical analysis for dispersion properties and losses has been carried out for a new type of Photonic crystal fiber where the air-holes are arranged in a circular pattern with a silica matrix called as Circular Photonic Crystal Fiber (C-PCF). The dependence of different PCF geometrical parameters namely different circular spacings, air-hole diameter and numbers of air-hole rings are carried out in detail towards practical applications. Our numerical analysis establishes that total dispersion is strongly affected by the interplay between material dispersion and waveguide dispersion. For smaller air-filing fraction, adding extra air-hole rings does not change dispersion much whereas for higher air-filling fraction, the dispersion nature changes significantly. With proper adjustment of the parameters ultra-flattened dispersion could be achieved; though the application can be limited by higher losses. However, the ultra-flat dispersion fibers can be used for practical high power applications like supercontinuum generation (SCG) by reducing the loss at the pumping wavelength by increasing the no of air-hole rings. Broadband smooth SCG can also be achieved with low loss oscillating near-zero dispersion fiber with higher no of air-hole rings. The detail study shows that for realistic dispersion engineering we need to be careful for both loss and dispersion.

Gain and bandwidth investigation in a near-zero ultra-flat dispersion PCF for optical parametric amplification around the communication wavelength

In this work, we explore the fiber optical parametric amplifiers (FOPAs) gain and bandwidth spectra of near-zero ultra-flattened photonic crystal fibers (PCFs) around the communication wavelength. The parametric gain and spectral bandwidth have been explored for all the three zero-dispersion wavelengths (ZDWs) of the near-zero ultra-flat fiber. Our numerical analysis establishes a dispersion profile with D=0±0.35  ps/nm/km for a bandwidth of 440 nm around the communication wavelength to fully exploit the four-wave mixing effect with three ZDWs for broadband applications. It has been observed that the broader gain spectrum of FOPAs can be achieved with the near-zero and ultra-flattened dispersion curve with proper tuning of the pumping condition. A broader bandwidth with sufficient peak gain value has been achieved with small negative anomalous dispersion (β2≤0) and positive value of fourth-order dispersion parameter (+ve  β4) around the pumping wavelength. Wider bandwidth of the parametric amplifier has been observed around the second ZDW with a negative slope of the dispersion curve. A total bandwidth ≈520  nm could be achieved with the ultra-flat dispersion nature of the optimized PCF. The design methodology of achieving wider gain by tuning the pumping wavelength for favorable higher-order dispersion parameters would be very useful for future dispersion engineered devices.

Near-elliptic Core Triangular-lattice and Square-lattice PCFs: A Comparison of Birefringence, Cut-off and GVD Characteristics Towards Fiber Device Application

In this work, we report detailed numerical analysis of the near-elliptic core index-guiding triangular-lattice and square-lattice photonic crystal fiber (PCFs); where we numerically characterize the birefringence, single mode, cut-off behavior and group velocity dispersion and effective area properties. By varying geometry and examining the modal field profile we find that for the same relative values of

Designing an Ultra-Negative Dispersion Photonic Crystal Fiber with Square-Lattice Geometry

d/{\Lambda}

Tunable Fiber-Optic Parametric Amplifier Based on Near-Zero Ultraflat Dispersion PCF for Communication Wavelength

, triangular-lattice PCFs show higher birefringence whereas the square-lattice PCFs show a wider range of single-mode operation. Square-lattice PCF was found to be endlessly single-mode for higher air-filling fraction (

Yb-fiber laser pumped high-power, broadly tunable, single-frequency red source based on a singly resonant optical parametric oscillator

d/{\Lambda}

Tunable parametric amplifier for mid-IR application based on highly nonlinear chalcogenide material

). Dispersion comparison between the two structures reveal that we need smaller lengths of triangular-lattice PCF for dispersion compensation whereas PCFs with square-lattice with nearer relative dispersion slope (RDS) can better compensate the broadband dispersion. Square-lattice PCFs show zero dispersion wavelength (ZDW) red-shifted, making it preferable for mid-IR supercontinuum generation (SCG) with highly non-linear chalcogenide material. Square-lattice PCFs show higher dispersion slope that leads to compression of the broadband, thus accumulating more power in the pulse. On the other hand, triangular-lattice PCF with flat dispersion profile can generate broader SCG. Square-lattice PCF with low Group Velocity Dispersion (GVD) at the anomalous dispersion corresponds to higher dispersion length (

ASE suppression in a liquid filled dual core PCF for dispersion compensation

L_D

Single mode realization of low loss liquid filled birefringent photonic crystal fibers (PCFs)

) and higher degree of solitonic interaction. The effective area of square-lattice PCF is always greater than its triangular-lattice counterpart making it better suited for high power applications. We have also performed a comparison of the dispersion properties of between the symmetric-core and asymmetric-core triangular-lattice PCF. While we need smaller length of symmetric-core PCF for dispersion compensation, broadband dispersion compensation can be performed with asymmetric-core PCF. Mid-Infrared (IR) SCG can be better performed with asymmetric core PCF with compressed and high power pulse, while wider range of SCG can be performed with symmetric core PCF. Thus, this study will be extremely useful for designing/realizing fiber towards a custom application around these characteristics.