Resonant Microcavity Research Articles

High-sensitivity, low-noise, and stable fiber vibration sensor using an integrated fiber cantilever beam with surface plasmon resonance microcavities.

Fiber-optic vibration sensors have been studied widely owing to their anti-electromagnetic interference, corrosion resistance, and ease of integration and distribution. Previous reports primarily focused on the frequency detection of vibration signals. However, the amplitude sensitivity, noise-equivalent amplitude (NEA), and stability determine the sensing precision and accuracy of the device. The present work proposes a fiber-optic device for detecting vibration signals. A fiber cantilever beam in-line structure is integrated on the surface of the surface plasmon resonance (SPR) microcavity at the end facet of a single-mode fiber (SMF). The device can detect broadband vibration signals (1-150 kHz) under the experimental conditions in the study. The amplitude sensitivity of the device reaches 396.64 mV/µm at 100 kHz with a signal-to-noise ratio (SNR) of 61.5 dB at 0.41µm, and the NEA of the device is as low as 2.97 pm/Hz1/2 with good linearity in frequency detection. In the absence of any feedback control system, the device has a low standard deviation of 2.15% in response to vibration signals, limited by the stability of our optical testing system. The developed device is a perfect combination of fiber configuration, miniaturization, high sensitivity, and stability, making it a promising candidate for detecting vibration signals in the future.

Research on coupling excitation and detection of capillary microcavity resonance

Research on coupling excitation and detection of capillary microcavity resonance

High sensitivity detection of influenza virus using polymer-coated microcavity biosensor

Influenza viruses are a major global public health concern because they cause seasonal epidemics and sporadic pandemics. The sensitivity and specificity of viral detection can be improved through recent developments in biosensor technology. The capacity of microcavity biosensors to detect biomolecules, including viruses, in real-time without requiring labels caused interest among them. In this study, we present a novel polymer-coated microcavity biosensor for the high-sensitivity detection of the H1N1 influenza virus. The main microcavity structure of this label-free biosensor is intended to improve sensitivity by optimizing performance characteristics specific to viral samples. The simulation indicates the microcavity resonator’s outstanding sensitivity in H1N1. Our biosensor efficiently detects H1N1 at lower concentrations than conventional diagnostic techniques by utilizing a polymer coating that improves binding affinity and encourages the immobilization of certain antibodies. Using the polymer layer enhances the sensor’s functionality and confers biocompatibility, opening up possible uses in point-of-care environments. The polymer-coated microcavity biosensor, according to our research, is a potential platform for early, sensitive, and quick influenza virus detection, greatly assisting with public health response and monitoring activities.

Study on properties of microcavity resonance of AlGaInP based hexagonal photonic crystal

Study on properties of microcavity resonance of AlGaInP based hexagonal photonic crystal

Enhancing Performance in Top‐Illuminated Shortwave Infrared Organic Photodetectors via Microcavity Resonance

AbstractShortwave infrared (SWIR) image sensors have unique functions in many optical applications, leading to widespread attention in developing next‐generation materials and photodetector technologies. Organic photodetectors (OPDs) are highly promising due to their flexibility in molecular design and processability. However, integrating OPDs with silicon readout integrated circuits (ROICs) poses numerous challenges, often resulting in underestimated device performance and limiting technological progress. To address the requirements of integrating top‐illuminated OPD with ROICs and to enhance the external quantum efficiency (EQE), optical microcavities are introduced into the OPDs. The EQE in the SWIR region can be effectively enhanced by properly adjusting the thicknesses of the photoactive layer (PAL) and interlayers. Simulations of the optical field distribution further support the active functions of the microcavity structure. The spatial variation of the microcavities allows the spectral response to shift from 1000 to 1400 nm, and the optimized device achieves an EQE of 25.8% at 1260 nm. Finally, the OPDs are integrated with a silicon‐based test kit, and the results reveal comparable sensing performance, demonstrating the high potential of microcavity resonance for device integration. This design effectively improves the integration of OPDs with traditional ROICs and advances SWIR‐based organic image sensor technology further toward commercialization.

Highly reflective and high-Q thin resonant subwavelength gratings

Abstract We theoretically investigate the design of thin subwavelength gratings possessing high-reflectivity and high-Q resonances when illuminated at normal incidence by a Gaussian beam. We compare the performances of single-period and dual-period rectangular gratings using finite element method-based optimization and predict a close to two orders of magnitude improvement (×90) in their transmission loss-linewidth product, which is the relevant figure of merit for e.g. resonant mirror-based microcavity applications.

High performance CH3NH3PbI3 perovskite photodetector functionalized by T-Ag plasmonic nanostructure

Photodetectors with ultrathin thickness and high efficiency are increasingly needed in the developing of wearable devices. However, the very limited active layer thickness has seriously restricted the photoelectric conversion efficiency. Here, the optical nanostructure fabricated with the assistance of self-assembly polystyrene mask layer has been integrated to increase the light absorption capacity by simultaneously utilizing the local surface plasma resonance, gap plasma, and the microcavity resonance effect. With the incorporation of triangular silver (T-Ag) nanostructure, the photogenerated current and response speed have significantly enhanced 481.25% and 26.30%, respectively. This strategy provides a viable way to design high-efficiency ultra-thin photodetectors.

Probing microcavity resonance spectra with intracavity emitters

Probing microcavity resonance spectra with intracavity emitters

Active strong coupling of exciton and nanocavity based on GSST-WSe2 hybrid nanostructures

The strong coupling between optical resonance microcavity and matter excitations provides a practical path for controlling light-matter interactions. However, conventional microcavity, whose functions are fixed at the fabrication stage, dramatically limits the modulation of light-matter interactions. Here, we investigate the active strong coupling of resonance mode and exciton in GSST-WSe2 hybrid nanostructures. It is demonstrated that significant spectral splitting is observed in single nanostructures, tetramers, and metasurfaces. We further confirm the strong coupling by calculating the enhanced fluorescence spectra. The coupling effect between the excited resonance and exciton is dramatically modulated during the change of GSST from amorphous to crystalline, thus realizing the strong coupling switching. This switching property has been fully demonstrated in several systems mentioned earlier. Our work is significant in guiding the study of actively tunable strong light-matter interactions at the nanoscale.

Ultra-compact all optical 4–2 encoder based on micro-cavity resonators

Ultra-compact all optical 4–2 encoder based on micro-cavity resonators

Organic Photoplethysmography Sensor Based on Directional Emission Microcavity Organic Light‐Emitting Device

AbstractWearable photoplethysmography (PPG) sensors provide real‐time monitoring of essential human health parameters by integrating a light source with a photodetector. However, they face a common challenge: the presence of a faint pulsating (AC) signal amidst a highly noisy and drifting non‐pulsatile background. This necessitates fine‐tuning how the light is spread out to make sure that a significant number of emitted photons carry vital physiological information and trigger the detector's photocurrent. An innovative organic PPG sensor with a microcavity organic light‐emitting diode (OLED) that emits light in a controlled direction, coupled with an annular organic photodetector (OPD) is demonstrated here. By adjusting the OLED's cavity lengths, the microcavity resonance peak is shifted, achieving angled directional emission. Placing the microcavity OLEDs at the center of the annular OPD enhances the portion of light that reflects from arterial vessels in the skin and tissues. This increases the AC signal for recording arterial vessel pulsations by 47.66%. This advancement simplifies sensor recognition and achieves an unprecedented low power consumption of only 9.96 µW for heart rate sensing, meeting essential recognition criteria.

High-Q Tamm plasmon-like resonance in spherical Bragg microcavity resonators.

This work proposes what we believe to be a novel Tamm plasmon-like resonance supporting structure consisting of an Au/SiO2 core-shell metal nanosphere structure surrounded by a TiO2/SiO2 spherical Bragg resonator (SBR). The cavity formed between the core metal particle and the SBR supports a localized mode similar to Tamm plasmons in planar dielectric multilayers. Theoretical simulations reveal a sharp absorption peak in the SBR bandgap region, associated with this mode, together with strong local field enhancement. We studied the modification of a dipolar electric emitter's radiative and non-radiative decay rates in this resonant structure, resulting in a quantum efficiency of ∼90% for a dipole at a distance of r=60n m from the Au nanosphere surface. A 30-layer metal-SBR Tamm plasmon-like resonant supporting structure results in a Q up to ∼103. The Tamm plasmon-like mode is affected by the Bragg wavelength and the number of layers of the SBR, and the thickness of the spacer cavity layer. These results will open a new avenue for generating high-Q Tamm plasmon-like modes for switches, optical logic computing devices, and nonlinear applications.

Controllable Fabrication of Organic Semiconductors for Aligned Microlasers and Integrated Photodetectors

AbstractEngineering of organic single crystal toward controllable and aligned patterns at microscale is crucial to the realization of highly integrated organic photonic devices and optoelectronics. However, precise positioning and controllable morphology of crystal structures is still challenging due to the strict conditions for crystal growth. In this paper, a solution based crystal regulation strategy with the assistance of template‐constrained growth method and femtosecond laser processing technology is developed to prepare aligned crystalline microribbon arrays. Simple solvent evaporation results in the random distribution and orientation of self‐assembled crystalline microribbons while it tends to form highly crystalline and orderly microribbon arrays assisted by the confined template microchannels. The large‐scale microribbon array can be fabricated as organic photodetectors with sensitive and fast response under 405 nm illumination. By virtue of the femtosecond laser processing technique, the microribbon arrays are precisely processed into a series of crystal subunits and each microribbon subunit can function as an individual microcavity resonator to produce stable, high‐quality organic laser. The facile solution based template‐constrained self‐assembly and femtosecond laser processing method provide novel strategies to generate highly oriented and controllable crystal structures for the potential applications in integrated organic lasers and optoelectronics.

Hollow Microcavity Electrode for Enhancing Light Extraction.

Luminous efficiency is a pivotal factor for assessing the performance of optoelectronic devices, wherein light loss caused by diverse factors is harvested and converted into the radiative mode. In this study, we demonstrate a nanoscale vacuum photonic crystal layer (nVPCL) for light extraction enhancement. A corrugated semi-transparent electrode incorporating a periodic hollow-structure array was designed through a simulation that utilizes finite-difference time-domain computational analysis. The corrugated profile, stemming from the periodic hollow structure, was fabricated using laser interference lithography, which allows the precise engineering of various geometrical parameters by controlling the process conditions. The semi-transparent electrode consisted of a 15 nm thick Ag film, which acted as the exit mirror and induced microcavity resonance. When applied to a conventional green organic light-emitting diode (OLED) structure, the optimized nVPCL-integrated device demonstrated a 21.5% enhancement in external quantum efficiency compared to the reference device. Further, the full width at half maximum exhibited a 27.5% reduction compared to that of the reference device, demonstrating improved color purity. This study presents a novel approach by applying a hybrid thin film electrode design to optoelectronic devices to enhance optical efficiency and color purity.

Quantifying local stiffness and forces in soft biological tissues using droplet optical microcavities

Mechanical properties of biological tissues fundamentally underlie various biological processes and noncontact, local, and microscopic methods can provide fundamental insights. Here, we present an approach for quantifying the local mechanical properties of biological materials at the microscale, based on measuring the spectral shifts of the optical resonances in droplet microcavities. Specifically, the developed method allows for measurements of deformations in dye-doped oil droplets embedded in soft materials or biological tissues with an error of only 1 nm, which in turn enables measurements of anisotropic stress inside tissues as small as a few pN/μm2. Furthermore, by applying an external strain, Young's modulus can be measured in the range from 1 Pa to 35 kPa, which covers most human soft tissues. Using multiple droplet microcavities, our approach could enable mapping of stiffness and forces in inhomogeneous soft tissues and could also be applied to in vivo and single-cell experiments. The developed method can potentially lead to insights into the mechanics of biological tissues.

Optical resonance and chaos control in a Reuleaux-triangle microcavity

Optical resonance and chaos control in a Reuleaux-triangle microcavity

Coherent control of scattering and absorption in organic microresonators

We study coherent perfect absorption in organic microcavity resonators and extend these principles and our findings to more complex microresonator systems that, beyond absorption, also possess additional cavity energy dissipation mechanisms. The experimental approach uses laser interferometry to closely monitor the energy fluxes within the system at all device ports as a function of the device geometry and the phase relationships of the incident beams. A particular focus is on optical systems based on 2nd order Bragg gratings, which are crucial for the operation of organic distributed feedback (DFB) lasers or as light incouplers in optical waveguiding films. Coherent control allows the diffraction efficiency of the underlying grating to be tuned over a wide range of values. This strategy allows significant optimisation of resonator structures for high efficiency light coupling in optical waveguides and fine tuning of grating parameters for the most efficient optical mode conversion.

Highly Sensitive Temperature Sensor Based on PDMS Sensitized Hollow Micro-cavity Resonator

Highly Sensitive Temperature Sensor Based on PDMS Sensitized Hollow Micro-cavity Resonator

Boosting infrared absorption through surface plasmon resonance enhanced HgCdTe microcavity

As one of the most widely used infrared (IR) detectors, a mercury cadmium telluride (MCT) detector usually requires liquid nitrogen refrigeration to suppress thermally activated noise mechanisms that are inherent to its narrow bandgap, which limits its practical applications. Therefore, it is essential to develop strategies to suppress dark current with reduced cooling demand. In this work, a surface plasmon resonance (SPR) enhanced MCT microcavity was proposed to intensify optical absorption across a broadband while diminishing the thickness of the MCT layer to reduce intrinsic dark current proportional to the volume of the absorber. The microcavity is formed by sandwiching the MCT layer between a top well-designed hybrid golden-cross antenna array and a bottom golden reflector. The microcavity is employed to trap the incident light to amplify the absorption, and the golden-cross antenna array is introduced to not only significantly enhance the incident light field through the SPR effect but also to broaden the microcavity resonant mode. Numerical calculation indicated that an absorptance exceeding 95.3% can be attained at 3.4 μm with the full width at half maxima (FWHM) extending beyond 1.38 μm, which almost covers the absorption band of MCT in mid-wavelength IR (MWIR), all while the MCT layer is only 530 nm. Moreover, the prototype device unit was fabricated and tested. Measured peak absorption reached 98.7% @ 3.6 μm and FWHM was as broad as 1.12 μm. These results demonstrate that the high and wideband absorption in an ultrathin MCT layer is achieved based on the synergistic effects of SPR and microcavity resonance.

Design of tunable photothermal porous thermal emitter based on nonreciprocal effect

Tunable thermal emitters have become a research hotspot for high-efficiency, low-loss novel thermal radiation devices. It has been found that the tunability of thermal radiation devices can be greatly strengthened and the efficiency of photothermal conversion enhanced through the tuning of the radiation temperature by magneto-optical microstructures. In this paper, a novel porous thermal emitter for the mid-infrared band is designed and the interconnection between nonreciprocal radiation and photothermal conversion is investigated for the first time. The three-hole column (THC) porous structure is optimized from the traditional one-hole column (OHC) porous structure. Through detailed analysis of the light incident angle, external magnetic field strength, and hole diameter, it is shown that the strong nonreciprocal radiation is due to the variation of the cavity structure parameters, which enhances the microcavity resonance effect, thereby enhancing the surface plasmon resonance (SPR) on the porous surface. The electric field contours at different positions also visualize the enhancement mechanism of SPR for nonreciprocal radiation. It has been investigated that different magnetic field strengths and porous structures have significant impact on nonreciprocal thermal tuning. The nonreciprocal system can be used to tune the local heat around the hole, and the temperature difference increase as nonreciprocal effects is greater as the magnetic field strength and input power increases. This work also provides new ideas for the application of thermal emitters and the design of energy conversion devices.