High-quality factor in a symmetrical metal-cladding optical waveguide

The enhanced light–matter interaction provides a significant way to reveal information about the matter. Within a confining light in a small-sized microcavity is an important issue in both nonlinear optics and waveguides. Here, we present a symmetrical metal-cladding optical waveguide (SMCOW) with a high-quality factor [Formula: see text] which possesses numerous superior performances, such as high sensitivity and high power density, due to the excited ultrahigh-order modes oscillating between the top and bottom layer at a very small incident angle to standing wave field. The relationship between thickness, angle and [Formula: see text] is obtained from experimental detection and theoretical simulation, with a high-quality factor [Formula: see text]. Meanwhile, we have deduced the equation of an important parameter, the half-width [Formula: see text] of the attenuated total reflectance (ATR) peak, which is dependent on the imaginary part of the propagation constant Im[Formula: see text] and incident angle [Formula: see text].