Binary subwavelength structures that act simultaneously as antireflective and diffractive structure for the mid-infrared wavelength range

We present a single-layer of binary subwavelength structures designed to reduce Fresnel reflections at an interface while providing an efficient diffractive function

Design and quality evaluation of micro-optical freeform beam shapers

A method to generate thin micro-optical freeform (MOF) beam shapers by wrapping a much thicker freeform surface is provided. The influence of parameters such as the clipping factor q, the design wavelength and the spectrum of the light source into the quality of the output distributions has been studied

Exotic optical elements generating 2D surface waves

We introduce exotic optical elements for 2D surface wave systems hosting Bloch surface waves (BSWs). First, we will study a 2D non-diffracting beam, second, a 2D array of the optical bottle beam via the Talbot effect and third, tight light confinement like a photonic nanojet. Investigations are carried out using a well-established BSW platform

Coherent broadband light source for parallel optical coherence tomography

A Ti:sapphire planar waveguide is rib structured by Ar ion milling to provide parallel channel waveguides. By coupling high-power pump light through a microlens array into the waveguides, a novel broadband luminescent parallel emitter is demonstrated as a light source for parallel optical coherence tomography using smart detector arrays

Refraction limit of miniaturized optical systems: A ball-lens example

We study experimentally and theoretically the electromagnetic field in amplitude and phase behind ball-lenses across a wide range of diameters, ranging from a millimeter scale down to a micrometer. Based on the observation, we study the transition between the refraction and diffraction regime. The former regime is dominated by observables for which it is sufficient to use a ray-optical picture for an explanation, e.g., a cusp catastrophe and caustics. A wave-optical picture, i.e. Mie theory, is required to explain the features, e.g., photonic nanojets, in the latter regime. The vanishing of the cusp catastrophe and the emergence of the photonic nanojet is here understood as the refraction limit. Three different criteria are used to identify the limit: focal length, spot size, and amount of cross-polarization generated in the scattering process. We identify at a wavelength of 642 nm and while considering ordinary glass as the ball-lens material, a diameter of approximately 10 µm as the refraction limit. With our study, we shed new light on the means necessary to describe micro-optical system. This is useful when designing optical devices for imaging or illumination

Demonstration of Bloch Surface Waves in crystals with LiNbO3 thin films

A novel one dimensional photonic crystal (1DPHC) sustaining Bloch surface waves (BSWs) with a single crystal thin film lithium niobate (TFLN) as a part of a multilayer is theoretically and experimentally investigated. Properties of the dielectric multilayer platform with optical anisotropy introduced by X-cut TFLN are studied