Advanced Photonics Research最新文献

An advanced complementary metal-oxide-semiconductor (CMOS)compatible graphene/silicon multispectral active metasurfaces are investigated based on guided-mode resonance filters. The simulated results show a high extinction ratio (>25 dB), narrow linewidth (≈1.5 @1550 nm), quality factor of Q ≈ 1000, and polarization-insensitive operation. By taking advantage of graphene broadband absorption, the device operation is presented in the multiple spectral bands (NIR-MIR) using simple geometrical scaling rules. The same device architecture can be employed for combined electro-optic and thermo-optic tuning using graphene as an integrated microheater. This work contributes to the development of advanced broadband silicon-based active metasurfaces for tunable spectral filters and laser mirrors, optical switches, modulators, and sensors.

The development of modern optical communication systems requires specific waveguides, given that the widely used fiber-optic components are poorly integrated with planar technologies. For planarization in the millimeter-wave and subterahertz bands, so-called gap waveguides are proposed, offering low-loss performance and cost-efficient manufacturing. Hence, the utilization of this technology in the optical range is very promising. Herein, a strategy for designing gap waveguides made of two metasurfaces composed of dielectric disk-shaped resonators operated in hybrid HE (magnetic dipole) and EH (electric dipole) modes is proposed. The coupled dipole model is applied to the complex multiple-scattering problem by substituting each resonator as an electric and magnetic dipole, providing equations for the efficient calculation of metasurface reflection and transmission properties. It is demonstrated that with the correct choice of metasurface geometry providing their resonant reflection conditions, a waveguide channel can be implemented between a pair of metasurfaces, which allows propagation of the transverse electric and transverse magnetic waves similar to those of a parallel plate waveguide with perfectly conducting either electric or magnetic walls. This approach may be seen as a novel metasurface-based waveguide structure that uses flexibly mediated boundary conditions to control electromagnetic wave propagation.

Germanium-containing short-wave infrared (SWIR) avalanche photodiode (APD) arrays on silicon platforms have the potential for monolithic integration into complementary metal-oxide-semiconductor (CMOS) integrated circuits, making them mass-manufacturable, high-performance, arrayed optical detectors operating at wavelengths beyond the silicon cut-off wavelength. Here, the first high-performance, surface-illuminated, 10-pixel linear array of pseudoplanar geometry germanium-on-silicon (Ge-on-Si) APDs operating at 1550 nm wavelength and at temperatures up to 378 K are demonstrated. At room temperature, the dark current, avalanche gain, responsivity, and avalanche breakdown of the devices show good uniformity. Array A exhibits a mean dark current density of 198 ± 62 mA cm⁻² at 90% of the breakdown voltage. The excess noise factor is less than half that of InP-based SWIR APD arrays, which allows Ge-on-Si devices to operate at a higher avalanche gain. A responsivity of 8.2 A W⁻¹ at a gain of 20 and excess noise of 3.3 is achieved when illuminated with 1550 nm wavelength light. The detector array also demonstrates stable performance at 378 K with a maximum avalanche gain of 24. This device architecture will be applicable for the design of large-scale APD arrays on Si platforms for SWIR detection which can be used in imaging, sensing, and optical communication applications.

A high-isolation liquid crystal on silicon (LCoS)-based optical switch realized by genetic algorithm (GA)-assisted method for parameterized hologram generation is proposed and experimentally demonstrated. The proposed method can simultaneously suppress all higher order diffraction crosstalk caused by the fringing of the electric field in LCoS. The hologram on the LCoS is parameterized, and a GA is employed to efficiently find out the optimal parameters. The simulation results indicate that the crosstalk induced by high-order diffraction beams can be reduced to below −50 dB over 100 operational cycles.

This review comprehensively examines the optical chaos generation and its diverse applications, focusing on recent advancements in this field. Optical chaos, characterized by its sensitivity to initial conditions and unpredictability, has been extensively utilized in secure communication, physical random number generation, and high-precision measurement and sensing. The review explores three primary methods for generating chaotic lasers, optical feedback, optical injection, and optoelectronic feedback. It highlights the significance of bandwidth enhancement and time-delay signature suppression in improving chaos quality. Key applications include secure communication and key distribution via chaos synchronization, physical random number generation for cryptography, and chaotic lidar for centimeter-level target detection, chaotic correlation optical time-domain reflectometry for fiber fault detection, and chaotic distributed optical fiber sensing for temperature monitoring. Additionally, the review discusses the emerging role of chaotic laser in terahertz noise generation. Future challenges and opportunities are also outlined. It is hoped that this review can facilitate the development of chaos theory and inspire new application scenarios of chaotic laser.

Materials exhibiting hyperbolic dispersion have attracted considerable interest within the optical and quantum communities due to their potential to confine electromagnetic waves at subwavelength scales, thereby surpassing the diffraction limit. This capability arises from the support of high-k (i.e., wavevector) eigenmodes in hyperbolic materials. However, a substantial trade-off exists between energy confinement and dissipation of these high-k eigenmodes under ambient conditions, with the fundamental limits of this trade-off remaining unexplored. Herein, the concept of hyperbolic asymptotic eigenmodes is studied, which are high-k eigenmodes that align with the asymptotic direction, as the name implies. Additionally, the challenge of mitigating the losses associated with these modes in hyperbolic metamaterials is addressed. This is achieved by carefully tuning the permittivity tensors of these metamaterials to satisfy loss compensation, where the ratio of the real to imaginary parts of the perpendicular and parallel components is equal. The findings demonstrate that hyperbolic asymptotic eigenmodes exhibit strong confinement and long-range propagation. Furthermore, proof-of-concept simulations for hyperbolic asymptotic eigenmodes in active hyperbolic metamaterials with gain molecules at visible frequencies are presented. The proposed loss compensation of hyperbolic asymptotic eigenmodes holds promise for advancing both conventional and quantum electromagnetic signal processing.