Herwig Kogelnik

Bio: Herwig Kogelnik is an academic researcher. The author has contributed to research in topics: Diffraction & Blazed grating. The author has an hindex of 3, co-authored 3 publications receiving 5714 citations.

Coupled wave theory for thick hologram gratings

Abstract: A coupled wave analysis is given of the Bragg diffraction of light by thick hologram gratings, which is analogous to Phariseau's treatment of acoustic gratings and to the “dynamical” theory of X-ray diffraction. The theory remains valid for large diffraction efficiencies where the incident wave is strongly depleted. It is applied to transmission holograms and to reflection holograms. Spatial modulations of both the refractive index and the absorption constant are allowed for. The effects of loss in the grating and of slanted fringes are also considered. Algebraic formulas and their numerical evaluations are given for the diffraction efficiencies and the angular and wavelength sensitivities of the various hologram types.

Imaging of optical modes — resonators with internal lenses

Abstract: This paper discusses the modes of optical resonators, and optical modes of propagation or Gaussian beams of light. The passage of Gaussian beams through lenses, telescopes, sequences of lenses, and lenslike media is studied. Mode matching formulae are derived. A complex beam parameter is introduced for which the law of transformation by any given optical structure can be written in the simple form of a bilinear transformation (ABCD law). Resonators with internal optical elements and their transmission line duals are also investigated. Effective Fresnel numbers and curvature parameters are determined which allow one to infer the diffraction losses, the resonant conditions, and the mode patterns of the various systems. Results are obtained for resonators with internal lenses, sequences of lenses with irises inserted between the lenses, resonators with internal lenslike media, transmission lines consisting of a lenslike medium with periodically spaced irises, and resonators with one very large mirror.

Coupled Wave Theory for Thick Hologram Gratings

Abstract: A coupled wave analysis is given of the Bragg diffraction of light by thick hologram gratings, which is analogous to Phariseau's treatment of acoustic gratings and to the “dynamical” theory of X-ray diffraction. The theory remains valid for large diffraction efficiencies where the incident wave is strongly depleted. It is applied to transmission holograms and to reflection holograms. Spatial modulations of both the refractive index and the absorption constant are allowed for. The effects of loss in the grating and of slanted fringes are also considered. Algebraic formulas and their numerical evaluations are given for the diffraction efficiencies and the angular and wavelength sensitivities of the various hologram types.

Laser Beams and Resonators

Abstract: This paper is a review of the theory-of laser beams and resonators. It is meant to be tutorial in nature and useful in scope. No attempt is made to be exhaustive in the treatment. Rather, emphasis is placed on formulations and derivations which lead to basic understanding and on results which bear practical significance.

Rigorous coupled-wave analysis of planar-grating diffraction

Abstract: A rigorous coupled-wave approach is used to analyze diffraction by general planar gratings bounded by two different media. The grating fringes may have any orientation (slanted or unslanted) with respect to the grating surfaces. The analysis is based on a state-variables representation and results in a unifying, easily computer-implementable matrix formulation of the general planar-grating diffraction problem. Accurate diffraction characteristics are presented for the first time to the authors’ knowledge for general slanted gratings. This present rigorous formulation is compared with rigorous modal theory, approximate two-wave modal theory, approximate multiwave coupled-wave theory, and approximate two-wave coupled-wave theory. Typical errors in the diffraction characteristics introduced by these various approximate theories are evaluated for transmission, slanted, and reflection gratings. Inclusion of higher-order waves in a theory is important for obtaining accurate predictions when forward-diffracted orders are dominant (transmission-grating behavior). Conversely, when backward-diffracted orders dominate (reflection-grating behavior), second derivatives of the field amplitudes and boundary diffraction need to be included to produce accurate results.

Coupled‐Wave Theory of Distributed Feedback Lasers

Abstract: An analysis of laser action in a periodic structure is presented. A model of two counter‐running waves coupled by backward Bragg scattering is used. The resonant frequencies and threshold criteria for the modes of oscillation have been determined for both index and gain periodicities. Analytical approximations are given for both the high‐ and low‐gain cases, and computational results for the intermediate regimes.

Formation of Bragg gratings in optical fibers by a transverse holographic method

Abstract: Bragg gratings have been produced in germanosilicate optical fibers by exposing the core, through the side of the cladding, to a coherent UV two-beam interference pattern with a wavelength selected to lie in the oxygen-vacancy defect band of germania, near 244 nm. Fractional index perturbations of approximately 3 x 10(-5) have been written in a 4.4-mm length of the core with a 5-min exposure. The Bragg filters formed by this new technique had reflectivities of 50-55% and spectral widths, at half-maximum, of 42 GHz.