Laser & Photonics Reviews

Journal: Laser & Photonics Reviews

Abbreviation

Laser & Photon. Rev.

Publisher

Wiley

ISSN

1863-8880
1863-8899

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Publications1 - 8 of 8

Flash Scanning Volumetric Optoacoustic Tomography for High Resolution Whole‐Body Tracking of Nanoagent Kinetics and Biodistribution
Ron, Avihai; Kalva, Sandeep K.; Periyasamy, Vijitha; et al. (2021)
Laser & Photonics Reviews
Tracking of biodynamics across entire living organisms is essential for understanding complex biology and disease progression. The presently available small‐animal functional and molecular imaging modalities remain constrained by factors including long image acquisition times, low spatial resolution, limited penetration or poor contrast. Here flash scanning volumetric optoacoustic tomography (fSVOT), a new approach for high‐speed imaging of fast kinetics and biodistribution of optical contrast agents in whole mice that simultaneously provides reference images of vascular and organ anatomy with unrivaled fidelity and contrast, is presented. The imaging protocol employs continuous overfly scanning of a spherical matrix array transducer, accomplishing a 200 µm resolution 3D scan of the whole mouse body within 45 s without relying on signal averaging. This corresponds to an imaging speed gain of more than an order of magnitude compared with existing state‐of‐the‐art implementations of comparable resolution performance. Volumetric tracking and quantification of gold nanoagent and near infrared (NIR)‐II dye kinetics and their differential uptake in various organs are demonstrated. fSVOT thus offers unprecedented capabilities for multiscale imaging of pharmacokinetics and biodistribution with high contrast, resolution, and speed.
Mixing Properties of Room Temperature Patch-Antenna Receivers in a Mid-Infrared (lambda approximate to 9 mu m) Heterodyne System
Bigioli, Azzurra; Gacemi, Djamal; Palaferri, Daniele; et al. (2020)
Laser & Photonics Reviews
A room‐temperature mid‐infrared (λ = 9 µm) heterodyne system based on high‐performance unipolar optoelectronic devices is presented. The local oscillator (LO) is a quantum cascade laser (QCL), while the receiver is an antenna coupled quantum well infrared photodetector optimized to operate in a microcavity configuration. Measurements of the saturation intensity show that these receivers have a linear response up to very high optical power, an essential feature for heterodyne detection. By providing an accurate passive stabilization of the LO, the heterodyne system reaches at room temperature the record value of noise equivalent power (NEP) of 30 pW at 9 µm and in the GHz frequency range. Finally, it is demonstrated that the injection of microwave signal into the receivers shifts the heterodyne beating over the large bandwidth of the devices. This mixing property is a unique valuable function of these devices for signal treatment in compact QCL‐based systems.
Noninvasive Near‐Field Spectroscopy of Single Subwavelength Complementary Resonators
Hale, Lucy L.; Keller, Janine; Siday, Thomas; et al. (2020)
Laser & Photonics Reviews
Controlling and Phase-Locking a THz Quantum Cascade Laser Frequency Comb by Small Optical Frequency Tuning
Consolino, Luigi; Campa, Annamaria; De Regis, Michele; et al. (2021)
Laser & Photonics Reviews
Full phase control of terahertz (THz)-emitting quantum cascade laser (QCL) combs has recently been demonstrated, opening new perspectives for even the most demanding applications. In this framework, simplifying the set-ups for control of these devices will help to accelerate their spreading in many fields. This study reports a new way to control the emission frequencies of a THz QCL comb by small optical frequency tuning (SOFT), using a very simple experimental setup, exploiting the incoherent emission of an ordinary white light-emitting diode. The slightly perturbative regime accessible in these conditions allows tweaking the complex refractive index of the semiconductor without destabilizing the broadband laser gain. The SOFT actuator is characterized and compared to another actuator, the QCL driving current. The suitability of this additional degree of freedom for frequency and phase stabilization of a THz QCL comb is shown and perspectives are discussed.
Engineering of the Second‐Harmonic Emission Directionality with III–V Semiconductor Rod Nanoantennas
Saerens, Grégoire; Tang, Iek; Petrov, Mihail I.; et al. (2020)
Laser & Photonics Reviews
The ability to engineer nonlinear optical emission from nanostructures is a key challenge to create efficient and compact components for integrated devices. This paper shows a method to control and manipulate the directionality of second‐harmonic generation emission by engineering geometry and position of rod nanoantennas. Single and dimer nanoantennas are fabricated by slicing III–V semiconductor nanowires with focused ion beam milling. The nonlinear optical response of nanoantennas is tailored by adjusting their length and position to achieve a targeted phase difference. The studied GaAs nanoantennas have a wurtzite structure that allows to achieve preferable directions for the second‐harmonic emission compared to a typical bulk zinc blende structure from top‐down fabricated nanostructures. Wurtzite nanoantennas provide a pure electric dipole response at the second‐harmonic wavelength, which together with pi‐phase control of emitted light is used for designing nonlinear emission patterns. The simulation results show how to redirect the second‐harmonic beam up to 30° and how to tailor the emission profile by adding elements. This method of second‐harmonic generation manipulation and phase array engineering can be applied to different types of nanowires and nanostructures. Nonlinear beam steering with structures from nanowires will foster the creation of compact optical components for integrated circuits.
11-GHz-Bandwidth Photonic Radar using MHz Electronics
Liu, Yang; Zhang, Ziqian; Burla, Maurizio; et al. (2022)
Laser & Photonics Reviews
The ever-increasing demand for high resolution and real-time recognition in radar applications has fuelled the development of electronic radars with increased bandwidth, high operation frequency, and fast processing capability. However, the generation and processing of wideband radar signals increase the hardware burden on complex and high-speed electronics, limiting its capability for applications that demand high spatial resolutions. Progress is being made, photonics-assisted radars offer higher frequencies but still heavily rely on costly and sophisticated high-frequency electronic devices such as benchtop digital microwave waveform generators that fundamentally constrain the bandwidth and the practical utility. Here, for the first time, a photonics-based radar with >11 GHz bandwidth (exceeding 20 GHz without RF antenna bandwidth limitation) driven and processed by simple MHz-level-electronics-based acoustic-optic modulation is demonstrated, which radically eliminates the requirement for ultra-fast GHz-speed electronics for wideband radar signal generation and processing. This wideband radar achieves centimeter-level spatial resolution and a real-time imaging rate of 200 frames s(-1), allowing for high-resolution detection of rapidly moving blades of an unmanned aerial vehicle. This radar provides an important technological basis for next-generation broadband radars with greatly reduced system complexity essential to ubiquitous sensing applications such as autonomous driving, environmental surveillance, and vital sign detection.
Coupled-Waveguides for Dispersion Compensation in Semiconductor Lasers
Bidaux, Yves; Kapsalidis, Filippos; Jouy, Pierre; et al. (2018)
Laser & Photonics Reviews
A dual waveguide for intracavity dispersion compensation in semiconductor lasers is presented and applied to a short mid‐infrared wavelength quantum cascade laser operating in the first atmospheric window ( 4.6 μm). As a result, stable comb operation on the full multi‐mode dynamical range is achieved in this device. Unlike previously proposed schemes, the dual waveguide approach can be applied to various types of semiconductor lasers and material systems. In particular, it could enable efficient group velocity dispersion compensation at near‐infrared wavelengths where semiconductor materials exhibit a large value of that parameter.
High-Speed Large-Field Multifocal Illumination Fluorescence Microscopy
Chen, Zhenyue; Mc Larney, Benedict; Rebling, Johannes; et al. (2020)
Laser & Photonics Reviews
Scanning optical microscopy techniques are commonly restricted to a sub‐millimeter field‐of‐view (FOV) or otherwise employ slow mechanical translation, limiting their applicability for imaging fast biological dynamics occurring over large areas. A rapid scanning large‐field multifocal illumination (LMI) fluorescence microscopy technique is devised based on a beam‐splitting grating and an acousto‐optic deflector synchronized with a high‐speed camera to attain real‐time fluorescence microscopy over a centimeter‐scale FOV. Owing to its large depth of focus, the approach allows noninvasive visualization of perfusion across the entire mouse cerebral cortex, not achievable with conventional wide‐field fluorescence microscopy methods. The new concept can readily be incorporated into conventional wide‐field microscopes to mitigate image blur due to tissue scattering and attain optimal trade‐off between spatial resolution and FOV. It further establishes a bridge between conventional wide‐field macroscopy and laser scanning confocal microscopy, thus it is anticipated to find broad applicability in functional neuroimaging, in vivo cell tracking, and other applications looking at large‐scale fluorescent‐based biodynamics.

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