Vladimir A. Sychugov

Coupling gratings as waveguide functional elements

Waveguide grating couplers allow the essential function of waveguide access to be integrated together with optical processing functions on a monolithic planar substrate. Grating coupling technology is topologically and, to a large extent, technologically compatible with the planar processes which define the optical processing waveguide circuit. Poor coupling efficiency, highly dispersive character, absence of user-friendly modelling tools and fabrication difficulties have long prevented this technology from being implemented into practical sensors and microsystems. This paper makes a review of the points where decisive technological progress has been made, illustrates some useful features of waveguide coupling gratings and underlines some of the difficulties which the designer may encounter.

Long-range surface plasmons in asymmetric layered metal-dielectric structures

Abstract This paper brings the experimental evidence of the existence of the long range plasmon mode in an asymmetrical thin metal film structure. This mode is identified theoretically and experimentally by means of the existence of the effect of abnormal reflection in the presence of a coupling corrugation grating. The use of this grating excited plasmon mode in sensor applications is discussed and early encouraging results are reported. The means for the very fast calculation of the effective index of the modes of a multilayer waveguide structure possibly comprising metal layers are presented.

Analytical treatment of the thermal problem in axially pumped solid-state lasers

A complete analytical analysis of the temperature distribution in a laser rod in an axial pumping scheme is presented. The heat source distribution, as well as the front or side cooling means, have a circularly cylindrical symmetry. The longitudinal heat-source distribution is strongly inhomogeneous.

Waveguide coupling gratings for high-sensitivity biochemical sensors

Grating coupling is now currently used in evanescent-wave biochemical sensors as a waveguide coupling element or as the sensing element. In most coupling cases of practical interest, the Rayleigh-Fourier method is valid, and leads to physically meaningful analytical solutions allowing grating coupling to be designed in simple terms. In the present paper the emphasis is placed on the grating as a waveguide coupling element.

Anomalous light reflection at the surface of a corrugated thin metal film

The process of excitation of surface electromagnetic waves (SEWs) in corrugated thin metal film is investigated theoretically and experimentally. The existence of an anomalous increase of the reflection coefficient is demonstrated. The excitation of long-range plasmons in thin metal films opens new possibilities for sensor applications.

Optimization and control of grating coupling to or from a silicon‐based optical waveguide

The analysis of a silicon-based step-index waveguide with a corrugation grating at its surface is performed by considering the reflec- tion between the silicon substrate and the optical buffer. The conditions on the silica buffer thickness for maximum in/out coupling into the sub- strate and into the air are given analytically, and a number of features of practical interest are described.

Waveguide excitation by a Gaussian beam and a finite size grating

The concrete problem of waveguide grating excitation by means of a finite size grating and a focused cylindrical incident beam is formulated with simplicity. A normalized chart gives the optimum excitation conditions of any coupling structure versus three normalized opto-geometrical parameters only.

Unidirectional waveguide grating coupling by means of parallelogrammic grooves

The blazing effect of parallelogramic grooves is analyzed theoretically and demonstrated experimentally in the case of TE and TM modes in large guidance waveguides. A novel fabrication method is proposed, modellized and demonstrated.

Demonstration of high-brightness-mode propagation in a compound waveguide structure

We demonstrate the existence of an unusual and useful high-brightness guided mode of a multimode AlGaAs/GaAs heterostructure compound slab waveguide. This mode has a narrow near-field single lobe confined to the low-index regions of the waveguide. This mode was selectively probed by optically exciting quantum wells optimally placed in the waveguide. By pumping in a stripe geometry, lasing is observed above a threshold of 80 kW/cm2 indicating efficient lasing in the highest-order waveguide mode. The near-field emission pattern of the waveguide was imaged to provide a direct measurement of the intensity profile of the higher-order mode.

Spectral selectivity of radiation-and tunnel-coupled waveguide structures

The spectral transmission profile of systems of radiation-and tunnel-coupled waveguides is studied. It is determined how a smooth variation of the thickness of the buffer layer in a structure consisting of a pair of tunnel-coupled waveguides with strongly varying parameters will affect the spectral properties of the system as a whole. A simple physical treatment of the operation of a number of integrated and fiber-optic devices is given, and the prospects for using the proposed structure of two tunnel-coupled waveguides to realize a microlaser with waveguide output is demonstrated.