- Article
Authors: Le, Trung Thanh (2018-04) - We propose a method for generating the electromagnetically induced transparency (EIT) like-transmission by using microring resonator based on cascaded 3 × 3 multimode interference (MMI) structures. Based on the Fano resonance unit created from a 3 × 3 MMI coupler with a feedback waveguide, two schemes of two coupled Fano resonator unit (FRU) are investigated to generate the EIT like transmission. The theoretical and numerical analysis based on the coupled mode theory and transfer matrix is used for the designs. Our proposed structure has advantages of compactness and ease of fabrication. We use silicon waveguide for the design of the whole device so it is compatible with the existing ...
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- Article
Authors: Le, Duy Tien; Le, Trung Thanh (2017) - We propose a new structure for creating the Fano resonance and electromagnetically induced transparency couplers. The structure is based on 4x4 multimode interference couplers. The proposed devides have advantages of compactness, large tolerance fabrication. The tranfer matrix method (TMM) and numerical methods are used for analytical analysis and design of the device.
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- Article
Authors: Le, Trung Thanh (2017) - We present for the first time a new method for creating Fano resonance by using only one 3x3 multimode interference (MMI) coupler with a feedback waveguide. We use the silicon waveguide for the whole design, so it is compatible with CMOS technology. The device is compact and has a large tolerance fabrication. In addition, many useful optical functions such as all-optical switches, filters and single-mode lasers can be realized using Fano-type transmission device. The transfer matrix method (TMM) and beam propagation method (BPM) are used to optimally design the structure. We show that by using the proposed structure, fast and slow light can be obtained.
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- Article
Authors: Le, Duy Tien; Nguyen, Manh Cuong; Le, Trung Thanh (2017) - A cascaded microring resonator based on silicon waveguides with an MMI (Multimode
Interference) based Sagnac reflector is proposed in this study. By controlling the coupling
coefficients with the used of the MMI based Sagnac reflector, the double of both pulse
delay and advancement for the slow and fast light can be achieved. The new structure can
produce the fast and slow light phenomenon on one chip with a double of the time delay
and pulse advancement. By using the Sagnac reflector, the device is very compact. Transfer
matrix method and FDTD (Finite Difference Time Domain) simulation are used to obtain the
characteristics of the device. The transmission, phase, group delay a...
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- Article
Authors: Le, Duy Tien; Nguyen, Manh Cuong; Le, Trung Thanh (2017) - A high bandwidth all-optical 3×3 switch based on general interference multimode interference (GI-MMI)
structure is proposed in this study. Two 3×3 multimode interference couplers are cascaded to realize an alloptical
switch operating at both wavelengths of 1550 nm and 1310 nm. Two nonlinear directional couplers at
two outer-arms of the structure are used as all-optical phase shifters to achieve all switching states and to
control the switching states. Analytical expressions for switching operation using the transfer matrix method are
presented. The beam propagation method (BPM) is used to design and optimize the whole structure. The
optimal design of the all-optical phase shifte...
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- Article
Authors: Le, Trung Thanh (2018-07) - This study proposes a novel optical integrated structure using only one 4x4 multimode interference (MMI) coupler with support of two microring resonators for glucose and ethanol sensor. Due to the presence of the analyte, the wavelength shift of the output spectrum is realized. The proposed structure can provide a high sensitivity of 721 nm/RIU, low detection limit of 2.8x105 and good figure of merit of 5x1016 for glucose sensing.
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- Article
Authors: Le, Trung Thanh (2018) - We review our recent work on optical biosensors based on microring resonators (MRR) integrated with 4x4 multimode interference (MMI) couplers for multichannel and highly sensitive chemical and biological sensors. The proposed sensor structure has advantages of compactness, high sensitivity compared with the reported sensing structures. By using the transfer matrix method (TMM) and numerical simulations, the designs of the sensor based on silicon waveguides are optimized and demonstrated in detail. We applied our structure to detect glucose and ethanol concentrations simultaneously. A high sensitivity of 9000 nm/RIU, detection limit of 2x10-4 for glucose sensing and sensitivity of 600...
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- Book chapter
Authors: Le, Trung Thanh (2018-08) - The ‘Advances in Optics: Reviews’ Book Series is published as an Open Access Books in order to significantly increase the reach and impact of these volumes, which also published in two formats: electronic (pdf) with full-color illustrations and print (paperback). The third of three volumes of this Book Series has organized by topics of high interest. In order to offer a fast and easy reading of each topic, every chapter in this book is independent and self-contained. All chapters have the same structure: first an introduction to specific topic under study; second particular field description including sensing or/and measuring applications. Each of chapter is ending by complete list of...
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- Article
Authors: Nguyen, Thi Anh Dao; Le, Trung Thanh (2019) - Epilepsy is one of the most common brain disorders. Electroencephalogram (EEG) is widely used in epilepsy diagnosis and treatment, with it the epileptic spikes can be observed. Tensor decomposition-based feature extraction has been proposed to facilitate automatic detection of EEG epileptic spikes. However, tensor decomposition may still result in a large number of features which are considered negligible in determining expected output performance. We proposed a new feature selection method that combines the Fisher score and p-value feature selection methods to rank the features by using the longest common sequences (LCS) to separate epileptic and non-epileptic spikes. The proposed me...
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- Article
Authors: Le, Duy Tien; Le, Trung Thanh; Cahill, Laurence W. (2018) - All-optical logic gates have attracted considerable attention over the past decade. They have found application as adders, subtractors, header recognizers, parity checkers and in encryption systems. In this paper, we present a new structure based on cascaded 4×4 and 2×2 multimode interference (MMI) couplers for implementing optical XOR, XNOR, NAND and OR logic gates. The emphasis of the design is on optimising bandwidth and fabrication tolerance. Such a design would be useful for optical label swapping and recognition in optical packet switching networks. We use silicon on insulator (SOI) waveguides that are compatible with the CMOS technology, for designing the whole device. The Beam...
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- Article
Authors: Le, Duy Tien; Do, The Duong; Nguyen, Van Khoi; Nguyen, Anh Tuan; Le, Trung Thanh (2017) - We propose a method for generating the tunable Fano resonance line
sharp by using only one 4x4 multimode interference (MMI) coupler.
We show that our new device structure acting an interferometer and
we employ a microring resonator and phase shifter to control the
shape. The analytical analysis and FDTD simulations have been used
for the first order design. The device has advantages of compactness,
high tolerance fabrication and ease of fabrication on the same chip.
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