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Analysis and Design of Optical Devices by Colloidal Nano-Structures
, M.Sc. Thesis Sharif University of Technology ; Akbari, Mahmood (Supervisor)
Abstract
The colloidal crystals are formed of spherical particles and can be fabricated using simple and low-cost chemical methods. Optical properties of colloidal crystals should be recognized properly in order to design optical devices based on these nano-structures. Reflection and transmission coefficients of these multilayer structures are very important for understanding their properties. Semi-analytical methods like Fourier Modal method (FMM) can be very useful to obtain their reflection and transmission properties of these multilayer structures. In this thesis, we try to implement Matched Coordinate (MC) and Adaptive Spatial Resolution (ASR) techniques in the FMM. These techniques increase...
Determination of complex modes in photonic crystal waveguides using the phase variation in characteristic coefficients
, Article Optics Letters ; Volume 37, Issue 15 , 2012 , Pages 3078-3080 ; 01469592 (ISSN) ; Khavasi, A ; Sarrafi, P ; Mehrany, K ; Sharif University of Technology
OSA Pub
2012
Abstract
An efficient frequency-domain method, the phase variation monitoring (PVM) method, is proposed to determine the electromagnetic eigenmodes in two-dimensional photonic crystal waveguides. The proposed method is based on monitoring the reflection and transmission coefficients of incident plane waves. It is successfully applied to an illustrative line-defect photonic crystal waveguide and proved to be capable of calculating the in-plane leakage through the finite-size photonic crystal surrounding the line-defect. Calculation of the leakage loss is not only important for proper understanding of wave propagation within the defect but also for its significant role in applications of photonic...
A novel method for band structure analysis of photonic crystal slabs
, Article IEEE Photonics Journal ; Volume 3, Issue 6 , 2011 , Pages 1111-1122 ; 19430655 (ISSN) ; Akbari, M ; Mehrany, K ; Sharif University of Technology
2011
Abstract
We propose a new method to extract the modes of photonic crystal slabs and, thus, obtain their band structures. These slabs, which are 2-D periodic structures with finite thickness, can completely confine light and have the important advantage of simple construction for applications in integrated optic devices. In this paper, reflection pole method (RPM) is utilized to analyze photonic crystal slabs. Modes are poles of reflection and transmission coefficients of multilayered structures. According to this principle, modes can be detected by only pursuing phase variations of transmission coefficients that are equal to π rad. Therefore, extraction of modes becomes fast and simple through...
Invariant activity detection of a constant magnitude signal with unknown parameters in white Gaussian noise
, Article IET Communications ; Volume 3, Issue 8 , 2009 , Pages 1420-1431 ; 17518628 (ISSN) ; Tadaion, A. A ; Gazor, S ; Nayebi, M. M ; Sharif University of Technology
2009
Abstract
The authors propose invariant tests for the detection of a complex signal with unknown constant amplitude and unknown phase variation in additive white Gaussian noise (AWGN). The authors show that in this problem, the uniformly most powerful invariant (UMPI) detector does exist only if the number of samples N is two. For more than two samples N≥3, the authors derive the most powerful invariant (MPI) detector in known signal-to-noise ratio (SNR) and use its performance as the upper bound benchmark for any invariant test. In addition, the authors derive the generalised likelihood ratio (GLR) detector and evaluate its performance against the MPI performance bound. This detector is very simple...