Photonics

18 pages, 3235 KiB

Open AccessReview

Light–Matter Interaction of Single Quantum Emitters with Dielectric Nanostructures

by Lina Jaya Diguna, Liliana Tjahjana, Yudi Darma, Shuwen Zeng, Hong Wang and Muhammad Danang Birowosuto

Photonics 2018, 5(2), 14; https://doi.org/10.3390/photonics5020014 - 13 Jun 2018

Cited by 7 | Viewed by 8212

Abstract

Single quantum emitters are critical components for many future quantum information technologies. Novel active material systems have been developed and transitioned into engineering efforts at nanoscale. Here, we review recent progress of diverse quantum emitters and their optical properties, including fluorescent point defect [...] Read more.

Single quantum emitters are critical components for many future quantum information technologies. Novel active material systems have been developed and transitioned into engineering efforts at nanoscale. Here, we review recent progress of diverse quantum emitters and their optical properties, including fluorescent point defect in bulk and single nanocrystal, two-dimensional materials, and quantum dots (QDs). Remarkable progress has also been made in controlling spontaneous emission by utilizing the local density of optical states in dielectric photonic nanostructures. We focus on the enhanced light–matter interaction between the emitter and cavity, enabling the realization of efficient and fast single photon sources. Full article

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9 pages, 2575 KiB

Open AccessArticle

Ge-Core/a-Si-Shell Nanowire-Based Field-Effect Transistor for Sensitive Terahertz Detection

by Xiangying Deng, Marolop Simanullang and Yukio Kawano

Photonics 2018, 5(2), 13; https://doi.org/10.3390/photonics5020013 - 29 May 2018

Cited by 12 | Viewed by 4344

Abstract

Although terahertz technology has demonstrated strong potential for various applications, detectors operating in the terahertz region are yet to be fully established. Numerous designs have been proposed for sensitive terahertz detection, with a nanowire-based field-effect transistor (FET) being one of the most promising [...] Read more.

Although terahertz technology has demonstrated strong potential for various applications, detectors operating in the terahertz region are yet to be fully established. Numerous designs have been proposed for sensitive terahertz detection, with a nanowire-based field-effect transistor (FET) being one of the most promising candidates. In this study, we use a Ge-core/a-Si-shell nanowire coupled to a bow-tie antenna to fabricate a FET structure for terahertz detection. We achieved high responsivity and low noise equivalent power (NEP) upon irradiation at 1.63 THz. The proposed sensitive terahertz detector will further promote the development of terahertz technology in fields such as spectroscopic analysis and imaging. Full article

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18 pages, 3132 KiB

Open AccessArticle

Range Information Characterization of the Hokuyo UST-20LX LIDAR Sensor

by Matthew A. Cooper, John F. Raquet and Rick Patton

Photonics 2018, 5(2), 12; https://doi.org/10.3390/photonics5020012 - 23 May 2018

Cited by 28 | Viewed by 6271

Abstract

This paper presents a study on the data measurements that the Hokuyo UST-20LX Laser Rangefinder produces, which compiles into an overall characterization of the LiDAR sensor relative to indoor environments. The range measurements, beam divergence, angular resolution, error effect due to some common [...] Read more.

This paper presents a study on the data measurements that the Hokuyo UST-20LX Laser Rangefinder produces, which compiles into an overall characterization of the LiDAR sensor relative to indoor environments. The range measurements, beam divergence, angular resolution, error effect due to some common painted and wooden surfaces, and the error due to target surface orientation are analyzed. It was shown that using a statistical average of sensor measurements provides a more accurate range measurement. It was also shown that the major source of errors for the Hokuyo UST-20LX sensor was caused by something that will be referred to as “mixed pixels”. Additional error sources are target surface material, and the range relative to the sensor. The purpose of this paper was twofold: (1) to describe a series of tests that can be performed to characterize various aspects of a LIDAR system from a user perspective, and (2) present a detailed characterization of the commonly-used Hokuyo UST-20LX LIDAR sensor. Full article

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14 pages, 4024 KiB

Open AccessFeature PaperArticle

Broadband Terahertz Light–Matter Interaction Enhancement for Precise Spectroscopy of Thin Films and Micro-Samples

by Romain Peretti, Flavie Braud, Emilien Peytavit, Emmanuel Dubois and Jean-François Lampin

Photonics 2018, 5(2), 11; https://doi.org/10.3390/photonics5020011 - 17 May 2018

Cited by 21 | Viewed by 6022

Abstract

In biology, molecules and macromolecules such as sugars, proteins, DNA, RNA, etc., are of utmost importance. Detecting their presence as well as getting information on their actual structure is still a challenge in many cases. The vibrational states of such molecules correspond to [...] Read more.

In biology, molecules and macromolecules such as sugars, proteins, DNA, RNA, etc., are of utmost importance. Detecting their presence as well as getting information on their actual structure is still a challenge in many cases. The vibrational states of such molecules correspond to a spectral range extending from infrared to terahertz. Spectroscopy is used for the detection and the identification of such compounds and their structure. Terahertz spectroscopy of a biosample is challenging for two main reasons: the high terahertz absorption by water molecules in the sample; and the small size of the sample—its volume is usually smaller than the cube of the terahertz wavelength, thus the light–matter interaction is extremely reduced. In this paper, we present the design, fabrication, characterization, and first typical use of a biophotonic device that aims to increase the light–matter interaction to enable terahertz spectroscopy of very small samples over a broad band (0.2–2 THz). Finally, we demonstrate the validity of our approach by time-domain spectroscopy of samples of a few µL. Full article

(This article belongs to the Special Issue Microwave Photonics 2017)

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18 pages, 3346 KiB

Open AccessReview

Site-Controlled Quantum Emitters in Dilute Nitrides and their Integration in Photonic Crystal Cavities

by Giorgio Pettinari, Marco Felici, Francesco Biccari, Mario Capizzi and Antonio Polimeni

Photonics 2018, 5(2), 10; https://doi.org/10.3390/photonics5020010 - 15 May 2018

Cited by 12 | Viewed by 3906

Abstract

We review an innovative approach for the fabrication of site-controlled quantum emitters (i.e., single-photon emitting quantum dots) based on the spatially selective incorporation and/or removal of hydrogen in dilute nitride semiconductors (e.g., GaAsN). In such systems, the formation of stable N-H complexes removes [...] Read more.

We review an innovative approach for the fabrication of site-controlled quantum emitters (i.e., single-photon emitting quantum dots) based on the spatially selective incorporation and/or removal of hydrogen in dilute nitride semiconductors (e.g., GaAsN). In such systems, the formation of stable N-H complexes removes the effects that nitrogen has on the alloy properties, thus enabling the in-plane engineering of the band bap energy of the system. Both a lithographic approach and/or a near-field optical illumination—coupled to the ultra-sharp diffusion profile of H in dilute nitrides—allow us to control the hydrogen implantation and/or removal on a nanometer scale. This, eventually, makes it possible to fabricate site-controlled quantum dots that are able to emit single photons on demand. The strategy for a deterministic spatial and spectral coupling of such quantum emitters with photonic crystal cavities is also presented. Full article

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16 pages, 2839 KiB

Open AccessReview

Advances in Retinal Optical Imaging

by Yanxiu Li, Xiaobo Xia and Yannis M. Paulus

Photonics 2018, 5(2), 9; https://doi.org/10.3390/photonics5020009 - 27 Apr 2018

Cited by 27 | Viewed by 6811

Abstract

Retinal imaging has undergone a revolution in the past 50 years to allow for better understanding of the eye in health and disease. Significant improvements have occurred both in hardware such as lasers and optics in addition to software image analysis. Optical imaging [...] Read more.

Retinal imaging has undergone a revolution in the past 50 years to allow for better understanding of the eye in health and disease. Significant improvements have occurred both in hardware such as lasers and optics in addition to software image analysis. Optical imaging modalities include optical coherence tomography (OCT), OCT angiography (OCTA), photoacoustic microscopy (PAM), scanning laser ophthalmoscopy (SLO), adaptive optics (AO), fundus autofluorescence (FAF), and molecular imaging (MI). These imaging modalities have enabled improved visualization of retinal pathophysiology and have had a substantial impact on basic and translational medical research. These improvements in technology have translated into early disease detection, more accurate diagnosis, and improved management of numerous chorioretinal diseases. This article summarizes recent advances and applications of retinal optical imaging techniques, discusses current clinical challenges, and predicts future directions in retinal optical imaging. Full article

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24 pages, 1100 KiB

Open AccessFeature PaperReview

Shaping Light in Backward-Wave Nonlinear Hyperbolic Metamaterials

by Alexander K. Popov, Sergey A. Myslivets, Vitaly V. Slabko, Victor A. Tkachenko and Thomas F. George

Photonics 2018, 5(2), 8; https://doi.org/10.3390/photonics5020008 - 18 Apr 2018

Cited by 5 | Viewed by 4424

Abstract

Backward electromagnetic waves are extraordinary waves with contra-directed phase velocity and energy flux. Unusual properties of the coherent nonlinear optical coupling of the phase-matched ordinary and backward electromagnetic waves with contra-directed energy fluxes are described that enable greatly-enhanced frequency and propagation direction conversion, [...] Read more.

Backward electromagnetic waves are extraordinary waves with contra-directed phase velocity and energy flux. Unusual properties of the coherent nonlinear optical coupling of the phase-matched ordinary and backward electromagnetic waves with contra-directed energy fluxes are described that enable greatly-enhanced frequency and propagation direction conversion, parametrical amplification, as well as control of shape of the light pulses. Extraordinary transient processes that emerge in such metamaterials in pulsed regimes are described. The results of the numerical simulation of particular plasmonic metamaterials with hyperbolic dispersion are presented, which prove the possibility to match phases of such coupled guided ordinary and backward electromagnetic waves. Particular properties of the outlined processes in the proposed metamaterial are demonstrated through numerical simulations. Potential applications include ultra-miniature amplifiers, frequency changing reflectors, modulators, pulse shapers, and remotely actuated sensors. Full article

(This article belongs to the Special Issue Nonlinear Dielectric Photonics and Metasurfaces)

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10 pages, 3804 KiB

Open AccessFeature PaperArticle

Impedance-Matched, Double-Zero Optical Metamaterials Based on Weakly Resonant Metal Oxide Nanowires

by Diego R. Abujetas, Ramón Paniagua-Domínguez and José A. Sánchez-Gil

Photonics 2018, 5(2), 7; https://doi.org/10.3390/photonics5020007 - 28 Mar 2018

Viewed by 4630

Abstract

Artificial optical metamaterial with a zero index of refraction holds promise for many diverse phenomena and applications, which can be achieved with vacuum (or related) surface impedance and materials in the optical domain. Here, we propose simple metal-oxide nanorods as meta-atoms on the [...] Read more.

Artificial optical metamaterial with a zero index of refraction holds promise for many diverse phenomena and applications, which can be achieved with vacuum (or related) surface impedance and materials in the optical domain. Here, we propose simple metal-oxide nanorods as meta-atoms on the basis of an effective medium approach, based on their weak overlapping (electric/magnetic) resonances. We thus studied the optical properties of

{TiO}_{2}

nanowire arrays with a high-filling fraction through their photonic band structure, which exhibits a double-degeneracy point without a band gap at the center of the Brillouin zone. Various configurations are considered that reveal their performance over a reasonable range of incident wave vectors as impedance-matched, double-zero, bulk (low-loss) metamaterials. Full article

(This article belongs to the Special Issue Nonlinear Dielectric Photonics and Metasurfaces)

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12 pages, 17659 KiB

Open AccessReview

Photonics-Based Microwave Image-Reject Mixer

by Dan Zhu and Shilong Pan

Photonics 2018, 5(2), 6; https://doi.org/10.3390/photonics5020006 - 26 Mar 2018

Cited by 48 | Viewed by 8082

Abstract

Recent developments in photonics-based microwave image-reject mixers (IRMs) are reviewed with an emphasis on the pre-filtering method, which applies an optical or electrical filter to remove the undesired image, and the phase cancellation method, which is realized by introducing an additional phase to [...] Read more.

Recent developments in photonics-based microwave image-reject mixers (IRMs) are reviewed with an emphasis on the pre-filtering method, which applies an optical or electrical filter to remove the undesired image, and the phase cancellation method, which is realized by introducing an additional phase to the converted image and cancelling it through coherent combination without phase shift. Applications of photonics-based microwave IRM in electronic warfare, radar systems and satellite payloads are described. The inherent challenges of implementing photonics-based microwave IRM to meet specific requirements of the radio frequency (RF) system are discussed. Developmental trends of the photonics-based microwave IRM are also discussed. Full article

(This article belongs to the Special Issue Microwave Photonics 2017)

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Photonics, Volume 5, Issue 2 (June 2018) – 9 articles

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