Influence Of Waveguide Research Articles

Measurements of quantum dot level populations using an optical waveguide

A scheme is proposed for measuring electron level populations in a semiconductor quantum dot embedded in a multimode waveguide. The photon transmittance of the waveguide under steady-state pumping is shown to depend on the presence of an electron in the ground state of the quantum dot. The influence of waveguide, quantum dot, and photon source parameters on the electron detection process is examined. It is shown that, even at a moderate mode Q-factor (104 to 105), the measurement contrast and signal-to-noise ratio are rather high (above 104). The feasibility of using the proposed method for probing the state of a charge qubit is discussed.

Tunable, narrow-band, grating-assisted microring reflectors

Tunable, grating-assisted ring resonator based optical mirrors are analyzed and their characteristics numerically evaluated. Mode number selection rules are presented to aid mirror optimization for high, narrow-band reflection and efficient sidelobe suppression. Data is presented on tuning sensitivity, on the effect of coupling on bandwidth and reflection coefficient, and on the influence of waveguide and grating loss on mirror performance. Group delay in the presence of loss and circuit parameter variations is also treated.

Cut off in its prime: the influence of waveguides on microwave technology

A paper by Lord Rayleigh, published in February 1897, was seminal in establishing the waveguide as a possible transmission medium which was `out of the ordinary' for the time and, in the event, some years ahead of its practical application. The waveguide is now well established as an engineering tool, especially where there is a requirement for high power along with high sensitivity and low loss. The behaviour of waveguides in the below cut-off region, where the attenuation does not become infinite but reaches an asymptotic value dependent on the guide dimensions, is now the basis of a primary standard of attenuation used in standards laboratories throughout the world. Despite the high attenuation, `propagation' in a waveguide in the cut-off mode has attracted interest recently through claims that the group velocity may be of the order of four times the velocity of light.

Investigation of the influence of a waveguide on changes in the parameters of acoustic emission signals

We investigate the influence of waveguides used in acoustic emission tests of materials in corrosive environments on changes in the parameters of acoustic emission (AE) signals. A method of boundary interpolation is suggested for determining the natural frequencies of the waveguides. This method enables one to perform calculations for cylindrical waveguides of various lengths and diameters. We present analytic relations used to select a waveguide with the required geometric parameters in agreement with the resonance bandwidth of an AE transducer. This selection reduces the losses of AE signals in passing through the waveguide. Experimental investigations of the attenuation of AE signals in the waveguide are also carried out.