Coherent perfect absorption in unpatterned thin films of intrinsic semiconductor
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RESEARCH ARTICLE
Coherent perfect absorption in unpatterned thin films of intrinsic semiconductor Md. Alamgir Badsha1
•
Md. Humaun Kabir1 • Mohammad Abdur Rashid1
Received: 6 August 2019 / Accepted: 13 July 2020 Ó The Optical Society of India 2020
Abstract We analyze the coherent perfect absorption (CPA) in unpatterned thin films in intrinsic semiconductor using the admittance matching method. The CPA is obtained at the phase and irradiance matching conditions. Controlling the modulation of relative input irradiances, a sharply single dip of CPA transforms to the broadband perfect absorption. The CPA parameters of admittance matching method are well agreement with the transfer matrix method. We analyze also coherently controlling the phase mechanism that is applicable for optical switching and modulation. This method provides the precision in design at visible regime. The method can enhance the design of future photonics devices for sensors and modulators. Keywords Thin film Absorption Modulation Optical switching
Introduction Bidirectional CPA is an optical phenomenon in an absorbing thin film or subwavelength periodic structure by interaction of two counter-propagating coherent waves. This makes the harnessing and harvesting the total loss of incoming electromagnetic waves by simply in the thin film structures would be the widely applicable in modulation devices of nanophotonics.
& Md. Alamgir Badsha [email protected] 1
Department of Physics, Jashore University of Science and Technology, Jashore 7408, Bangladesh
Unidirectional CPA is also obtainable in the artificial periodic or bilayer structures [1, 2]. PA by induced plasmons and omnidirectional super absorption are investigated in metamaterial [3, 4] as well. In a lossy waveguide rather than cavity, coupling and interference effects of light produce this mode [5]. Beyond these periodic structures, bidirectional CPA is the attractive topic in thin film of single or multilayer geometry. This was explained in timereversal anti-lasing effect below threshold condition in a thin film resonator [6]. Even subwavelength metallic object produces it by localized surface plasmons resonance effect [7]. The experimental interferometric control of CPA is also demonstrated [8] as interference effect [9–13]. In the corrugated metal film, CPA can be used for suppressing zeroth order and lead to the effective back bending of light [14]. Interference between counter propagating waves provides the enhanced coherent backscattering and appears the peak of reflection [15–19] in disordered media. In case of conducting thin film, the coherent superposition of frontscattered electron waves interfere destructively with the coherent backscattered electron waves by impurities as long as lasts the coherence state. This interference corresponds to weak localization the anomalous transport of mobile entities [20, 21]. Using a special mirror in ultrasonic imaging, overcoming the diffraction limit and hence the subwavelength focusing of microwave regime, timereversal effe
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