Optics letters最新文献

Organic semiconducting materials with a large magnetic field effect on photoluminescence (MFE_PL) are expected to be superior in innovative opto-spintronics. However, the magnitude of positive MFE_PL has remained relatively weak. While fluorinated graphene may give the favorable conditions for elevating the MFE_PL performance triggered by smaller spin-exchange interaction within intermolecular charge-transfer (CT) states, and it's MFE_PL has not been investigated. Here, we report a substantial positive MFE_PL, featuring a magnitude of 32.5% at room temperature, in few-layer fluorographene (FG) dispersed in hexanol under an applied magnetic field of 840 mT. Remarkably, the MFE_PL remains available at 17.65% when the field is reduced to 176 mT. Additionally, a large positive MFE_PL of 14.36% is observed in the FG:BCP composite film. We demonstrate that MFE_PL can be effectively tuned by controlling the FG layer number and the dielectric constant of the organic solvent used for dispersion. These findings reveal that the intermolecular charge-transfer (CT) states in donor-acceptor composites are contributors to the improved MFE_PL.

Skin-like organic light-emitting diodes (OLEDs) have garnered attention for their potential in wearable displays, implantable electronics, and biomedical sensing. However, creating high-resolution, mechanically stable OLEDs remains challenging. This study proposes a simple, non-destructive patterning technique to eliminate the thermal expansion mismatch between photoresist and ultra-thin elastomer films. Polyvinyl alcohol is used as a protective layer to allow the elastic ultra-thin films to be micro-patterned to within 2 µm, giving a resolution of up to 6349 pixels per inch (PPI). This work enhances the stability of micro-patterned pixel-defining layers (PDL) in optical manufacturing, thereby contributing to the development of high-resolution displays.

We demonstrate extreme-ultraviolet (EUV) spectroscopic ellipsometry (SE) using a tabletop high-harmonic generation (HHG) source for optical-constant determination. The polarization-resolved system enables accurate retrieval of the complex refractive index n-ik, as validated by measurements on a Nb₂O₅ film and by indirect determination of the optical constants of molybdenum and gold mirrors in the analyzer. This approach provides a compact and versatile platform for precise EUV optical-constant determination and future ultrafast studies.

In this Letter, a remote sensing method for measuring the fluorescence lifetime of aerosols is proposed, which combines the Mie-fluorescence lifetime-scattering (MFLS) model, established based on Mie and fluorescence lidar theory, with the golden section search algorithm. The feasibility of this method was verified through numerical simulations, which demonstrate its ability to measure aerosol fluorescence lifetime by using nanosecond laser pulses. Experimental studies were conducted using a Mie and dual-wavelength fluorescence lidar system on four types of fluorescent substances in aerosol form. The experimental results demonstrate that the proposed method can robustly measure aerosol fluorescence lifetimes on the nanosecond scale, achieving a minimum relative standard deviation of approximately 5.5%. Furthermore, when fluorescence lifetimes are employed as input features for a machine-learning classifier (K-nearest neighbors), the four fluorescent substances were classified with an accuracy of 96.9%. This method offers new opportunities for fluorescence lidar applications in fluorescence lifetime measurement.

Phase decorrelation can limit the dynamic range of phase-sensitive optical coherence elastography (PhS-OCE). Here, we reported a three-dimensional (3D) Bayesian neural network with an optimized sub-region size determination approach to overcome phase decorrelation rapidly in 3D-PhS-OCE. Our method can automatically provide a reasonable sub-region size as small as possible without requiring any prior knowledge. As a result, 3D pixel-level offsets induced by large deformations can be tracked rapidly, benefiting from both the smaller matching subregion and the network's parallel computing capability. The results demonstrate that the proposed 3D-BNN with optimal sub-region size determination improves computational efficiency by about 24% over the empirical 3D-BNN and by 26 times over the PVC method.

A high-precision signal demodulation scheme for fiber Bragg grating (FBG) is presented. The scheme utilizes a piezoelectric transducer (PZT) tuned co-located, multi-wavelength tunable FBGs (CMWT-FBGs) in one arm of the Michelson interferometer (MI), which adjusts its central-wavelength range to fully cover the wavelength shifts of the sensing FBG. The algorithm module utilizes a Savitzky-Golay (S-G) fitting algorithm to precisely locate the envelope peak of the interference signal, thereby accurately reconstructing the variations of the sensing FBG's central wavelength. Experimental results demonstrate that the modulation-demodulation scheme achieves a temperature accuracy of 1.33×10^-6°C and a strain accuracy of 1.04×10^-5με, respectively. These results show that the CMWT-FBGs-MI system offers a competitive advantage in high-speed and high-precision signal measurement, providing experimental and theoretical support for advancements in related fields.

Thin-film lithium niobate-on-insulator (LNOI) is a promising platform for integrated photonics, offering a large second-order nonlinearity for electro-optic modulation and nonlinear applications. In this work, we develop a plasmonic waveguide on the thin-film LN which can maintain high optical confinement. By careful design, the propagation losses can be reduced to 109 dB/cm and 462 dB/cm at 1550 nm in simulation and experiment, respectively. The plasmonic waveguide has an effective mode area of only 0.064 μm², which is one order of magnitude smaller than typical thin-film LNOI waveguides. These results represent, to our knowledge, the lowest optical losses reported to date for plasmonic waveguides fabricated on thin-film LNOI. The high optical confinement enables efficient light-matter interactions and can improve the modulation efficiency of electro-optic modulators in ultra-compact devices implemented on the thin-film LNOI platform.

In this work, 7.63 μJ few-cycle blue self-compressed soliton pulses are generated by combining efficient broadband frequency doubling, multiplate continuum (MPC) generation with blue pulse self-compression in He-filled hollow-capillary fibers (HCF). The multi-stage pre-compression setup creates optimal conditions for self-compression in HCF. By utilizing large-core HCFs instead of micro-structured fibers, we achieve a 7.63 μJ pulse energy. Dispersion analysis reveals the generation of a near-4.4 fs blue soliton. Numerical studies reveal our scheme's robustness under the perturbation of high-order dispersion and highlight its potential for energy scaling. Moreover, our scheme eliminates the dispersion management components for the final spectral broadening stage in post-compression schemes. This work paves the way for generating energetic ultrashort blue pulses, which show significant value in numerous strong-field and ultrafast applications.

We propose an all-optical terahertz (THz) multi-beam generation method that forms multiple spatially independent beams by optically multiplexing distinct wavelength pairs in a photomixer array. In this approach, wavelength-dependent delays induced by fiber chromatic dispersion impose precise phase gradients across array elements, enabling all-optical beam steering and multi-beam formation without any electronic phase shifters. In proof-of-concept experiments, two 300-GHz beams were simultaneously generated at -29° and +17°, in close agreement with the designed -30° and +20°. The identical beam directions observed in both single- and dual-beam operations confirm that each wavelength pair independently controls its corresponding THz beam. This concept demonstrates a compact, passive, and energy-efficient platform for wavelength-domain multi-beam control using standard fiber components.

The maximum baseline, and therefore resolution, of optical astronomical interferometers is limited by attenuation and phase noise within the optical path between the apertures and beam combiner, as well as the practical challenges of constructing optical delay lines more than a few hundred meters in length. We implement off-band phase stabilization on two fiber optic links of 85 km, creating a total baseline of 170 km. We show that the system is able to effectively phase stabilize signals from an incoherent pseudo-thermal source with a bandwidth of 11.2 nm. We are able to reduce the phase noise by 4-5 orders of magnitude between 1 and 100 Hz, such that we could resolve an applied phase difference of 0.16 cycles per second with continuous measurement. We show that, with phase stabilization active, the interferometer is able to recover both first-order and second-order photon correlations. These results demonstrate the feasibility of this technique for long-baseline optical and quantum astronomical interferometers. The present results are limited by chromatic dispersion within the fiber, which can be mitigated using dispersion-compensating modules.