There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Data Mining - Concepts and Techniques.

The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

Recently, monolithically integrated spot-size converters (SSCs) have increasingly been used to improve the butt-coupling efficiency between a single mode fiber and a semiconductor laser, without deteriorating the alignment tolerances. In this work, the simulated results presented show the expansion of the spot-size and consequently the increase in the coupling efficiency for various designs of spot-size converters. The reflection coefficients and a study of the alignment tolerances for such SSCs are also presented, as is the far field generated from the modal field profile of the lasers. A field expansion technique has been developed to estimate the evolution of the optical field near the laser facet.

http://ieeexplore.ieee.org/iel5/6657/17793/00821496.pdf

Rigorous study of near and far fields for spot-size converted semiconductor lasers

The evolution of the optical beam profile along a high-power tapered semiconductor amplifier has been demonstrated by using a rigorous finite element-based and full-vectorial modal approach, coupled with the beam propagation method. Numerically simulated results indicate that many higher order modes are generated and propagate along the tapered structure and their interference with the fundamental mode causes variations of the optical beam, both along the transverse and the axial directions, which significantly modifies the output beam quality.

Mode beating in tapered high-power deeply-etched semiconductor amplifiers

Modal solutions for photonic crystal fibers with circular air-holes in a hexagonal array are presented, by using a rigorous full-vectorial finite element-based approach. The effective indices, mode field profiles, spot-sizes, modal hybridness, modal birefringence and group velocity dispersion values are presented. The effect of external pressure on photonic crystal fibers is analyzed also by using the powerful finite element method. Modal solutions are obtained for both symmetric and asymmetric air-holes and the effect of pressure on the modal properties and mode degeneration are evaluated, presented and discussed.

Rigorous analysis of photonic crystal fibers by using a full-vectorial H-field-based finite element method

Modal solutions of photonic crystal fibers with both circular and rectangular air holes are presented by using a rigorous full vectorial finite element-based approach. The effective indices, mode field profiles, spot-sizes, power confinements, modal hybridness, beat lengths and group velocity dispersions are shown for the fundamental and higher order modes of the quasi-TE and TM polarizations. 1. INTRODUCTION The photonic crystal fiber (PCF) (which is also known as holey fiber), is a micro-structured fiber, where arrays of holes run along the waveguide length, having a more controllable fabrication parameters than standard single mode fiber. Increasing interest is being shown in such PCFs for a range of applications in optical communications, sensing and signal processing. These include the control and guidance of optical beams, taking advantage of their unique transmission characteristics, which include being continuously single-moded, with controllable spot-sizes and with tailored group velocity dispersion (GVD) characteristics. The optical properties of standard fibers are mostly controlled by two key parameters, the radius and the index difference between core and cladding. Single mode fiber can be designed by balancing these two parameters for different applications, for example in conventional low-loss telecommunication grade fibers or specialized fibers such as doped fibers with a smaller spot-size. However, the adjustment of the GVD properties is severely limited. By contrast in a PCF, the number of holes, their sizes, orientations and placements can provide an additional degree of freedom which is not present for conventional fiber. A wide range of potential applications is anticipated, exploiting the ability to tailor the GVD, the large spot-size for high power applications, and the smaller spot-size for improved nonlinear interactions, Raman amplification, Brillouin lasers, second harmonic generation, four-wave mixing, and creating polarization maintaining PCFs with higher modal birefringence and super continuum generation.

Modal solutions of photonic crystal fibers by finite element method

Finite element analysis based on the vector H-field formulation and incorporating the perturbation technique, is used to calculate the complex propagation characteristics of metal-coated dielectric waveguides for biophotonic applications.

Muttukrishnan Rajarajan

Papers

Rigorous study of near and far fields for spot-size converted semiconductor lasers

Mode beating in tapered high-power deeply-etched semiconductor amplifiers

Rigorous analysis of photonic crystal fibers by using a full-vectorial H-field-based finite element method

Modal solutions of photonic crystal fibers by finite element method

Characterization of Surface-Plasmon Resonance Based Sensors for Biophotonic Applications