Abstract Metamaterials and plasmonics are powerful tools for unconventional manipulation harnessing of light. can be engineered to possess intriguing properties lacking in natural materials, such as negative refractive index. Plasmonics offers capabilities confining light subwavelength dimensions enhancing light–matter interactions. Recently, the technological potential graphene-based has been recognized latter features large tunability, higher field-confinement lower loss compared with...

Abstract The magnetic circular dichroism and the Faraday rotation are fundamental phenomena of great practical importance arising from breaking time reversal symmetry by a field. In most materials, strength sign these effects can be only controlled field value its orientation. Furthermore, terahertz range is lacking materials having ability to affect polarization state light in non-reciprocal manner. Here we demonstrate, using broadband magneto-electro-optical spectroscopy, that graphene...

In this work we study metamaterial-enhanced graphene photodetectors operating in the mid-IR to THz. The detector element consists of a ribbon embedded within dual-metal split ring resonator, which acts like cavity enhance absorption electromagnetic radiation by ribbon, while asymmetric metal contacts enable photothermoelectric detection. Detectors designed for demonstrate peak responsivity (referenced total power) ∼120 mV/W at 1500 cm–1 and are employed spectroscopic evaluation vibrational...

Nanophotonic resonators can confine light to deep-subwavelength volumes with highly enhanced near-field intensity and therefore are widely used for surface-enhanced infrared absorption spectroscopy in various molecular sensing applications. The signal is mainly contributed by molecules photonic hot spots, which regions of a nanophotonic structure high-field intensity. Therefore, delivery the majority of, if not all, analyte spots crucial fully utilizing capability an optical sensor. However,...

A density-matrix based theory of transport and lasing in quantum-cascade lasers reveals that large disparity between luminescent linewidth broadening the tunneling transition changes design guidelines to favor strong coupling injector upper laser level. This conclusion is supported by experimental evidence.

We study plasmonic resonances in electrostatically gated graphene nanoribbons on silicon dioxide substrates. Absorption spectra are measured the mid-far-infrared and reveal multiple peaks, with width-dependent resonant frequencies. calculate dielectric function within random phase approximation show that observed can be explained by surface-plasmon–phonon–polariton modes, which arise from coupling of plasmon to three surface optical phonon modes dioxide.

Graphene-based plasmonic structures feature large tunability, high spatial confinement, and potentially low loss, are therefore an emerging technology for unconventional manipulation of light. In this paper, we demonstrate electrically tunable terahertz crystals consisting square-lattice graphene periodic anti-dot arrays on a SiO2/Si substrate. Transmission spectroscopy reveals multiple distinct resonances arising from excitations surface-plasmon–polariton (SPP) modes different branches the...

Surface-enhanced infrared absorption (SEIRA) spectroscopy can provide label-free, nondestructive detection and identification of analytes with high sensitivity specificity, therefore has been widely used for various sensing applications. SEIRA sensors usually employ resonant nanophotonic structures, which substantially enhance the electric field hence light-matter interactions by orders magnitude in certain nanoscale hot spots devices. However, as ever, smaller are employed to further field,...

The electron transit time of many different quantum cascade lasers has been measured and compared to the calculated upper laser level lifetimes with without taking into account interface roughness induced intersubband scattering. A significantly better correlation is found between experimental results calculation when including contribution from (corr. coeff.: 0.79 vs. 0.43 consideration roughness, respectively). This suggests that in addition longitudinal optical phonons, also crucial...

Near-room-temperature liquid metals offer unique and crucial advantages over solid for a broad range of applications which require soft, stretchable and/or reconfigurable structures devices. In particular, gallium-based are the most suitable wide applications, not only owing to their low melting points, but also thanks toxicity negligible vapor pressure. addition, exhibit attractive optical properties make them highly variety photonics applications. This review summarizes material metals,...

Faraday rotation is a fundamental property present in all non-reciprocal optical elements. In the THz range, graphene displays strong rotation; unfortunately, it limited to frequencies below cyclotron resonance. Here we show experimentally that specifically design metasurfaces, magneto-plasmons can be used circumvent this limitation. We find excellent agreement between theory and experiment provide new physical insights predictions on these phenomena. Finally, demonstrate tuneability...

Graphene plasmonics has recently found a variety of applications in terahertz photonic devices. High spatial confinement and large frequency tunability are two key advantages graphene plasmonics. Nevertheless, the tuning range plasmonic devices employing single-layer is ultimately limited by its carrier density range. Here, we demonstrate that graphene-based can be further extended multilayer structures. Both our experimental investigations theoretical calculations show gate-controlled...

Optical tweezers based on metallic plasmonic structures can achieve stable trapping of objects with deep subwavelength dimensions. However, due to the lack real-time tunability structures, manipulating trapped is challenging and usually requires sophisticated tuning excitation light source, which limits application scope such tweezers. Here, we propose operation principle analyze performance a two-dimensional (2D) network conveyor belts employing electrically tunable graphene simultaneously...

Exploiting several key characteristics of quantum cascade (QC) lasers, including wide tunability and room-temperature operation, the Quantum Cascade Laser Open-Path System (QCLOPS) was designed for detection a range trace gases field deployment in urban environments. Tunability over wavelength from 9.3 to 9.8 µm potentially provides capability monitoring ozone, ammonia, carbon dioxide, suite important air quality regional climate applications The 2008 Olympic Games Beijing, China drew...

We demonstrate single-mode quantum cascade lasers employing a folded Fabry-Perot cavity consisting of two straight sections connected by semicircular section in “hairpin” shape. These emitting at ∼4.5 μm are fabricated with identical processes as those for plain ridge lasers, and show strong suppression the comb modes, leading to tunable emission up 27 dB side mode ratio operating current range 60% above threshold when operated pulsed mode; is achieved from 80 ∼240 K.

Surface-enhanced Raman scattering (SERS) sensors typically employ nanophotonic structures that support high-field confinement and enhancement in hotspots to increase the from target molecules by orders of magnitude. In general, high field SERS can be achieved reducing critical dimensions mode volumes nanoscale. To this end, a multitude employing photonic with nanometric have been demonstrated. However, delivering analyte into is challenging, trade-off between confinement/enhancement delivery...

We employ properly designed asymmetric Mach-Zehnder interferometer structures as effective wavelength filters and monolithically integrate them in conventional Fabry-Perot cavities to facilitate single-mode operation of the lasers. With such type laser cavities, continuously tunable quantum cascade (QC) lasers is achieved pulsed mode from 80 K up room temperature continuous-wave with side-mode suppression ratio ∼35 dB. These devices are fabricated same process simple ridge lasers, therefore...

We demonstrate single-mode quantum cascade lasers emitting at ∼4.5 μm by employing a monolithic "candy-cane" shaped coupled-cavity consisting of straight section connecting one end to spiral section. The fabrication process is identical those for simple Fabry-Perot-type ridge lasers. Continuously tunable emission across ∼8 cm−1 with side mode suppression ratio up ∼25 dB and operating current range more than 70% above the threshold achieved when are operated in pulsed-mode from 80 K 155 K.

Quantum cascade lasers (QCLs) are complicated unipolar semiconductor devices based on intersubband transitions and resonant tunneling. In this study, femtosecond mid-infrared (Mid-IR) pulses employed to investigate the nature of carrier transport through active injector regions a room temperature, pulse biased ultrastrong coupling design QCL. Despite low average power (<;1 mW) Mid-IR pulses, efficient these into QCL waveguide made study nonlinear effects in QCLs possible. Biased just below...

Quantum Cascade devices with an emission wavelength centered around 5 μm have been shaped into compact, yet long (8 mm and 12 mm) spiral cavities to increase mid-infrared superluminescence (SL) power. Up ~57 mW of SL power at 250 K is obtained a Gaussian spectrum full width half maximum 56 cm(-1) coherence length ~107 μm.

We demonstrate amplification of longitudinal optical (LO) phonons by polar-optical interaction with an electron plasma in a GaAs structure coupled to metallic metasurface using two-color two-dimensional spectroscopy. In novel scheme, the metamaterial resonator enhances broadband terahertz fields, which generate coherent LO and drive free electrons conduction band GaAs. The time evolution phonon amplitude is monitored midinfrared pulses via LO-phonon-induced Kerr nonlinearity sample, showing...

We report our study on the effects of shortened quantum cascade (QC) laser injector regions. While conventional short-wavelength QC lasers typically have around seven or more region wells, we investigate structures with three and two wells. Improvements in threshold currents, output powers, wall-plug efficiencies are expected for fundamental reasons. At heat sink temperatures near 80 K, observe current densities less than 0.5 kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML"...

We report room temperature and milliwatt range mid-infrared superluminescent emission at 5 μm from Quantum Cascade (QC) devices. To achieve high power superluminescence, we utilize an ultrastrong coupling QC laser design, employ a cavity formed by the combination of 17° tilted cleaved facet wet etched rounded sloped to introduce additional mirror loss. For pulsed mode operation, 8 mm long 15 wide device achieves ∼1.3 mW peak 300 K 25 with Si3N4 anti-reflection coated ∼10.2 optical output 250 K.

Abstract Existing techniques for optical trapping and manipulation of microscopic objects, such as tweezers plasmonic tweezers, are mostly based on visible near‐infrared light sources. As it is in general more difficult to confine a specific length scale at longer wavelength, these have not been extended the mid‐infrared spectral region or beyond. Here, shown that by taking advantage fact many materials large permittivity dispersions region, using excitation can achieve additional...