Within the 61,000 m^2 ridge waveguide structure are five layers of InAs quantum dots, a key component of the QD lasers. In contrast to a p-doped-only laser, the co-doped laser displayed a substantial 303% decrease in threshold current and a 255% enhancement in maximum output power at ambient temperature. For co-doped lasers operating in a 1% pulse mode across temperatures of 15°C to 115°C, superior temperature stability is observed, with enhanced characteristic temperatures for both threshold current (T0) and slope efficiency (T1). The continuous-wave ground-state lasing of the co-doped laser is maintained stably up to an elevated temperature of 115°C. medical health The co-doping technique's potential to enhance silicon-based QD laser performance, leading to lower power consumption, higher temperature stability, and elevated operating temperatures, is evidenced by these findings, thereby fostering the advancement of high-performance silicon photonic chips.
In the study of nanoscale material systems' optical properties, scanning near-field optical microscopy (SNOM) plays a crucial role. Earlier publications documented how nanoimprinting enhances the repeatability and production rate of near-field probes, featuring intricate optical antenna structures like the 'campanile' probe. However, the difficulty of precisely controlling the plasmonic gap size, which directly influences the near-field enhancement and spatial resolution, remains significant. composite biomaterials A novel method for crafting a sub-20nm plasmonic gap in a near-field plasmonic probe is presented, utilizing controlled collapse of imprinted nanostructures, with atomic layer deposition (ALD) employed to precisely determine the gap's dimensions. The probe's apex exhibits an ultranarrow gap that induces a strong polarization-sensitive near-field optical response, increasing optical transmission over a wavelength range from 620 to 820 nm, enabling the analysis of tip-enhanced photoluminescence (TEPL) in two-dimensional (2D) materials. By employing a near-field probe, we demonstrate the potential of mapping a 2D exciton's coupling with a linearly polarized plasmonic resonance, with a spatial resolution below 30 nm. This work proposes a unique integration of a plasmonic antenna at the near-field probe's apex, thereby enabling crucial investigations of light-matter interactions at the nanoscale level.
We explore the optical losses in AlGaAs-on-Insulator photonic nano-waveguides, arising from sub-band-gap absorption, in this study. Through numerical simulations and optical pump-probe experiments, we observe a substantial effect of defect states on the capture and release of free carriers. The absorption of these defects demonstrates the widespread existence of the well-characterized EL2 defect, which is frequently located near oxidized (Al)GaAs surfaces. Our experimental observations, fortified by numerical and analytical models, provide vital parameters related to surface states, specifically absorption coefficients, surface trap density, and free carrier lifetime.
Improvements in light extraction efficiency have been a primary focus in the ongoing pursuit of enhanced organic light-emitting diodes (OLEDs). Among the proposed approaches for enhancing light extraction, the addition of a corrugation layer has proven to be a promising strategy, benefiting from its ease of implementation and high effectiveness. While a qualitative understanding of periodically corrugated OLEDs' function is achievable through diffraction theory, the quantitative analysis is hampered by the dipolar emission within the OLED structure, requiring finite-element electromagnetic simulations that may place a substantial burden on computational resources. For predicting the optical characteristics of periodically corrugated OLEDs, we introduce the Diffraction Matrix Method (DMM), a new simulation technique that allows for considerably faster calculation speeds, many orders of magnitude faster. Our method deconstructs the light emitted by a dipolar emitter into plane waves with varied wave vectors, and subsequently tracks their diffraction using diffraction matrices. A quantitative correspondence is observed between the calculated optical parameters and those predicted by the finite-difference time-domain (FDTD) method. The developed method's superiority over conventional approaches stems from its inherent ability to evaluate the wavevector-dependent power dissipation of a dipole. This enables a quantitative understanding of the loss channels in OLED structures.
Small dielectric objects can be precisely controlled using optical trapping, a technique that has proven invaluable in experimentation. However, the fundamental properties of conventional optical traps are inherently limited by diffraction, requiring high light intensities to effectively trap dielectric particles. A novel optical trap, based on dielectric photonic crystal nanobeam cavities, is presented in this work, substantially overcoming the limitations of standard optical trapping approaches. This accomplishment relies on an optomechanically induced backaction mechanism specifically between the dielectric nanoparticle and the cavities. To demonstrate complete levitation of a submicron-scale dielectric particle, our numerical simulations show a trap width of only 56 nanometers. The high trap stiffness results in a high Q-frequency product for the particle's motion, concurrently decreasing optical absorption by a factor of 43 in comparison to conventional optical tweezers. Furthermore, we present a case study illustrating the application of multiple laser wavelengths for crafting a complex, dynamic potential landscape with features below the diffraction limit. This optical trapping system, as demonstrated, offers unique possibilities for precision sensing and fundamental quantum experiments, leveraging the suspension of particles.
Multimode, bright squeezed vacuum, a non-classical light state with a macroscopic photon number, presents a promising avenue for encoding quantum information using its spectral degree of freedom. In the high-gain regime, we leverage a precise parametric down-conversion model, coupled with nonlinear holography, to engineer quantum correlations of bright squeezed vacuum within the frequency spectrum. Quantum correlations over two-dimensional lattice geometries, controlled all-optically, are proposed to enable ultrafast continuous-variable cluster state generation. In the frequency domain, we investigate the generation of a square cluster state, computing its covariance matrix and quantifying the quantum nullifier uncertainties, which demonstrate squeezing below the vacuum noise floor.
Our experimental investigation focuses on supercontinuum generation in potassium gadolinium tungstate (KGW) and yttrium vanadate (YVO4) crystals, with pumping using 210 fs, 1030 nm pulses from a 2 MHz repetition rate amplified YbKGW laser. The supercontinuum generation thresholds of these materials are substantially lower than those of sapphire and YAG, resulting in remarkable red-shifted spectral broadening (up to 1700 nm in YVO4 and up to 1900 nm in KGW). These materials also display reduced bulk heating during the filamentation process. Furthermore, the sample demonstrated a remarkable ability to withstand damage, maintaining consistent performance without any alteration, suggesting KGW and YVO4 as superior nonlinear materials for generating high-repetition-rate supercontinua within the near and short-wave infrared regions.
Inverted perovskite solar cells (PSCs) are alluring to researchers because of their advantages in low-temperature manufacturing, their insignificant hysteresis, and their adaptability with multi-junction solar cells. Despite being fabricated at low temperatures, perovskite films containing an abundance of undesirable defects do not enhance the performance of inverted polymer solar cells. This research explored a simple and effective passivation approach, where Poly(ethylene oxide) (PEO) was used as an antisolvent additive, to modify the perovskite film composition. Experiments and simulations confirm the ability of the PEO polymer to effectively neutralize interface imperfections in perovskite films. In inverted devices, the power conversion efficiency (PCE) saw an increase from 16.07% to 19.35%, a consequence of reduced non-radiative recombination achieved through PEO polymer defect passivation. Besides, the power conversion efficiency of unencapsulated PSCs, after PEO treatment, holds 97% of its original value when stored in a nitrogen-rich environment for 1000 hours.
Low-density parity-check (LDPC) coding methods are crucial for the consistent reliability of data within phase-modulated holographic data storage. Aiming to improve the speed of LDPC decoding, we introduce a reference beam-powered LDPC encoding technique for 4-phase-level phase-modulated holography. The process of decoding grants higher reliability to reference bits than to information bits, given that reference data are known during the recording and reading operations. Imidazoleketoneerastin The reference data, treated as prior information, elevates the significance of the initial decoding information (i.e., the log-likelihood ratio) for the reference bit within the low-density parity-check decoding procedure. The performance of the proposed methodology is assessed via simulations and practical experiments. The simulation results demonstrate that the proposed method, when compared with a conventional LDPC code with a phase error rate of 0.0019, achieves a 388% reduction in the bit error rate (BER), a 249% decrease in uncorrectable bit error rate (UBER), a 299% decrease in decoding iteration time, a 148% decrease in the number of decoding iterations, and a roughly 384% increase in decoding success probability. The outcomes of the trials unequivocally prove the supremacy of the suggested reference beam-assisted LDPC coding. By leveraging real-captured images, the developed method achieves a considerable decrease in PER, BER, decoding iterations, and decoding time.
Developing narrow-band thermal emitters operating at mid-infrared (MIR) wavelengths holds critical significance within numerous research fields. Results from prior investigations employing metallic metamaterials for MIR operation did not achieve narrow bandwidths, suggesting a deficiency in the temporal coherence of the obtained thermal emissions.