Browsing by Author "Chiang, Po-Jui"

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Design of metal-dielectric grating lasers only supporting surface-wave-like modes
(2014-11-17)
Chiang, Po-Jui
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Chang, Shu-Wei
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光電工程學系
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Department of Photonics
We present a prototype of semiconductor lasers with plasmonic periodic structures that only support transverse-magnetic modes at telecommunication wavelengths. The structure does not sustain transverse-electric guided modes which are irrelevant to surface-wave-enhanced applications, and lasing modes must be surface-wave-like. With thin low-index dielectric buffers near the metal surface, the threshold gain is kept at a decent level around the photonic band edge. Thin windows are then opened on the metal surface to let out significant surface fields. This facilitates usages of surface waves for the spectroscopy and sensing. (C) 2014 Optical Society of America
Efficient Photonic-Crystal Mode Solver: Eigenvalue Rather Than Generalized Eigenvalue Approach
(2016-03-01)
Chiang, Po-Jui
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Chang, Shu-Wei
;
光電工程學系
;
Department of Photonics
We present an iterative scheme to obtain guided Bloch modes in lossy and dispersive photonic crystals. The formulation is based on the concept of sources and transforms the quadratic generalized eigenvalue problem of modes into simpler eigenvalue counterpart for iterations. This feature makes it particularly useful in computations with large matrix sizes. Fewer memories and less computation time than those of conventional methods are required in these cases. The robustness of iterations is rooted in the reciprocity theorem for periodic Bloch parts. Through repeated estimations of propagation constants, Bloch modes of periodic structures converge quickly. Using this method, we take sinusoidal metal gratings as examples and demonstrate advantages of the scheme.
Frequency-domain formulation of photonic crystals using sources and gain
(2013-01-28)
Chiang, Po-Jui
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Chang, Shu-Wei
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光電工程學系
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Department of Photonics
We present a formulation to analyze photonic periodic structures from viewpoints of sources and gain. The approach is based on a generalized eigenvalue problem and mode expansions of sources which sustain optical fields with phase boundary conditions. Using this scheme, we calculate power spectra, dispersion relations, and quality factors of Bloch modes in one-dimensional periodic structures consisting of dielectrics or metals. We also compare the results calculated from this scheme with those from the complex-frequency method. The outcomes of these two approaches generally agree well and only deviate slightly in the regime of low quality factors. (C) 2013 Optical Society of America
THz Fiber Directional Coupler
(2007)
Chen, Hung-Wen
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Lu, Ja-Yu
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Chen, Li-Jin
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Chiang, Po-Jui
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Chang, Hung-Chun
We demonstrated a THz subwavelength fiber coupler for future millimeter wave applications. Unlike traditional optical fiber couplers, its coupling ratio is independent of the length of the coupling region because of the anti-symmetric mode cutoff. (C) 2007 Optical Society of America