The concept of modes in optics and photonics

ABSTRACT The concept of modes, or eigenfunctions, is fundamental for all wave phenomena in physics like optics, acoustics and quantum mechanics. In optics and photonics, the concept of modes is well suited to describe emission and absorption, coherence and interference, propagation and dispersion. The concept of modes consists of two aspects: first, the modes are solutions for the propagation of the light; second, the number of photons in the different modes describes the transport of energy or information. The energy density of the black body radiation, given by Planck's law, is the product of the density of modes in free space and the average number of photons per mode, given by the Bose-Einstein distribution. The transverse shape of the modes is determined by diffraction and boundary conditions. The longitudinal extension is given by the coherence length

Technology Outlook 2017

Über 20 ausgewiesene Fachleute beurteilen im «Technology Outlook 2017» die Chancen und Risiken technischer Entwicklungen für die Schweiz. Themen sind unter anderem Industrie 4.0, künstliche Intelligenz, Robotik oder neue Fertigungsverfahren. Die Schweiz verfügt über grosse Standortvorteile, doch teilweise besteht Nachholbedarf

High Resolution Interference Microscopy: A Tool for Probing Optical Waves in the Far-Field on a Nanometric Length Scale

High Resolution Interference Microscopy (HRIM) is a technique that allows the characterization of amplitude and phase of electromagnetic wave-fields in the far-field with a spatial accuracy that corresponds to a few nanometers in the object plane. Emphasis is put on the precise determination of topological features in the wave-field, called phase singularities or vortices, which are spatial points within the electromagnetic wave at which the amplitude is zero and the phase is hence not determined. An experimental tool working in transmission with a resolution of 20 nm in the object plane is presented and its application to the optical characterization of various single and periodic nanostructures such as trenches, gratings, microlenses and computer generated holograms is discussed. The conditions for the appearance of phase singularities are theoretically and experimentally outlined and it is shown how dislocation pairs can be used to determine unknown parameters from an object. Their corresponding applications to metrology or in optical data storage systems are analyzed. In addition, rigorous diffraction theory is used in all cases to simulate the interaction of light with the nano-optical structures to provide theoretical confirmation of the experimental results

Microlens systems for fluorescence detection in chemical microsystems

Micro-optical systems based on refractive microlenses are investigated. These systems are integrated on a chemical chip. They focus an excitation beam into the detection volume (microliter or even submicroliter scale) and collect the emitted light from fluorescent molecules. The fluorescence must be carefully separated by spatial and spectral filtering from the excitation. This paper presents the ray tracing simulation, fabrication, and measurement of three illumination systems. The measurements show that an adroit placement and combination of microfabricated lenses and stops can increase the separation between the excitation light and the fluorescence light. Moreover we present the successful detection of a 20 nM Cy5TM (Amersham Life Science Ltd.) solution in a 100-μm-wide and 50-μm-deep microchannel (excitation volume ≈250 pL) using one of these illumination systems. The microchemical chip with the micro-optical system has a thickness of less than 2 mm