Optical systems are often subject to parametric instability caused by the delayed response of the optical field to the system dynamics. In some cases, parasitic photothermal effects aggravate the instability by adding new interaction dynamics. This may lead to the possible insurgence or amplification of parametric gain that can further destabilize the system. In this paper, we show that the photothermal

Space-time wave packets (STWPs) constitute a broad class of pulsed optical fields that are rigidly transported in linear media without diffraction or dispersion, and are therefore propagation-invariant in the absence of optical nonlinearities or waveguiding structures. Such wave packets exhibit unique characteristics, such as controllable group velocities in free space and exotic refractive phenomena

Realizing efficient on-chip light sources has long been the “holy-grail” for Si-photonics research. Several important breakthroughs were made in this field in the past few years. In this article, we review the most recent advances in light sources integrated onto mainstream Si platforms and discuss four different integration technologies: Group IV light sources on Si, heterogeneous integration of III–V

Multiplexing and demultiplexing of optical orbital angular momentum (OAM) are critical operations in mode-division multiplexing communications. Traditional Dammann gratings, spiral phase planes, and optical geometric transformations are regarded as convenient methods for OAM mode (de)multiplexing. However, crosstalk between the different modes and the difficulty of mode multiplexing greatly limit their

Metasurfaces have powerful light field manipulation capabilities and have been researched and developed extensively in various fields. With an increasing demand for diverse functionalities, terahertz (THz) metasurfaces are also expanding their domain. In particular, integrating different functionalities into a single device is a compelling domain in metasurfaces. In this work, we demonstrate a functionally

Stainless steel is a basic raw material used in many industries. It can be customized by generating laser-induced periodic surface structure (LIPSS) as subwavelength gratings. Here, we present the capabilities of an LIPSS on stainless steel to modify the polarization state of the reflected radiation at the IR band. These structures have been modeled using the finite element method and fabricated by

Preparation, control, and measurement of optical vortices are increasingly important, as they play essential roles in both fundamental science and optical technology applications. Spatial light modulation is the main approach behind the control strategies, although there are limitations concerning the controllable wavelength. It is therefore crucial to develop approaches that expand the spectral range

Optical phased arrays (OPAs), the optical counterpart of phased arrays at radio frequencies, can electronically steer an optical beam without any moving parts. To achieve a 180° field of view (FOV), the array emitters should be spaced a half-wavelength apart or less. However, a conventional OPA based on a waveguide grating array suffers from strong cross talk between adjacent waveguides when the pitch

When an optical pulse is spatially localized in a highly multimoded waveguide, its energy is typically distributed among a multiplicity of modes, thus giving rise to a speckled transverse spatial profile that undergoes erratic changes with propagation. It has been suggested theoretically that pulsed multimode fields in which each wavelength is locked to an individual mode at a prescribed axial wavenumber

Measurement-device-independent quantum key distribution (MDIQKD) is a revolutionary protocol since it is physically immune to all attacks on the detection side. However, the protocol still keeps the strict assumptions on the source side that specify that the four BB84 states must be perfectly prepared to ensure security. Some protocols release part of the assumptions in the encoding system to keep

High-intensity pulse-beams are ubiquitous in scientific investigations and industrial applications ranging from the generation of secondary radiation sources (e.g., high harmonic generation, electrons) to material processing (e.g., micromachining, laser-eye surgery). Crucially, pulse-beams can only be controlled to the degree to which they are characterized, necessitating sophisticated measurement

In this work, a novel ultrafast optoelectronic proximity sensor based on a submillimeter-sized GaN monolithic chip is presented. Fabricated through wafer-scale microfabrication processes, the on-chip units adopting identical InGaN/GaN diode structures can function as emitters and receivers. The optoelectronic properties of the on-chip units are thoroughly investigated, and the ability of the receivers

Germanium-on-silicon (Ge-on-Si) avalanche photodiodes (APDs) are widely used in near-infrared detection, laser ranging, free space communication, quantum communication, and other fields. However, the existence of lattice defects at the Ge/Si interface causes a high dark current in the Ge-on-Si APD, degrading the device sensitivity and also increasing energy consumption in integrated circuits. In this

In this study, we present a high-efficiency InGaN red micro-LED fabricated by the incorporation of superlattice structure, atomic layer deposition passivation, and a distributed Bragg reflector, exhibiting maximum external quantum efficiency of 5.02% with a low efficiency droop corresponding to an injection current density of 112 A/cm2 . The fast carrier dynamics in the InGaN is characterized by using

Image data acquired with fused multispectral information can be used for effective identification and navigation owing to additional information beyond human vision, including thermal distribution, night vision, and molecular composition. However, the construction of photodetectors with such capabilities is hindered by the structural complexity arising from the integration of multiple semiconductor