Optical Microcavities Clad by Low-Absorption Electrode Media

Optical Microcavity: Sensing down to Single Molecules and Atoms

“…The original unperturbed Q factor is limited by radiation and scattering loss on the microcavity or by absorption of microcavity dielectric media. As an increase in the perturbation strength, the Q factor [26] is decreased to $Q\prime =\frac{Q-{\mathrm{italicQR}}_1/2-R_2/4}{1-R_1/2+{\mathrm{italicQR}}_2}$where $R_i=\frac{\int \Delta {\varepsilon }_i \left(\overrightarrow{r}\right){\left|E_j \left(\overrightarrow{r}\right)\right|}^{2}d\overrightarrow{r}}{\int \varepsilon \left(\overrightarrow{r}\right){\left|E_j \left(\overrightarrow{r}\right)\right|}^{2}d\overrightarrow{r}},\left\{i=1,2\right\}.$Further increase in the absorption dominates the microcavity loss mechanism so that the Q factor drops further to $Q\prime =\frac{Q}{1+{\mathrm{italicQR}}_2}\to \frac{1}{R_2}=\frac{\int \varepsilon \left(\stackrel{true\to }{r}\right){\left|{\overrightarrow{E}}_j \left(\overrightarrow{r}\right)\right|}^2{d}^{3}r}{\int \text{Im}\left[\Delta \varepsilon \left(\stackrel{true\to }{r}\right)\right]{\left|{\stackrel{true\to }{E}}_j \left(\overrightarrow{r}\right)\right|}^2{d}^{3}r}.$…”

“…This resonance change can be expressed in terms of permittivity change by the perturbation theory [ 26 ]. We assume that the unperturbed, non-magnetic system defined by ɛ ( r⃗ ) supports the mode j of resonance frequency ω j and modal electric field E⃗ j ( r⃗ ).…”

Terahertz Active Photonic Crystals for Condensed Gas Sensing

“…If the analyte shows an absorption in the frequency range of interest, the imaginary part of the refractive index and thereby the width of the resonance is varied [ 6 ]. More frequently, changes in the real part of the refractive index are sensed via shifts in the position of the resonance [ 6 ]. This explains also the use of high-Q cavities for sensing.…”

Design of sub-wavelength size indium tin oxide clad optical disk resonators with quality factors>10⁴ in visible wavelengths

“…However, sub-wavelength (sub-λ) size metallic resonators suffer from low Qfactors in the order of a few hundreds since conventional metallic materials such as gold and silver are extremely lossy in the visible and near-infrared wavelengths. On the other hand, compact optical cavities clad by low-loss transparent conductive oxide (TCO) electrodes are promising for room temperature (RT), continuous-wave (CW), current injection low-threshold micro-lasers due to significantly high Q-factors [3].In this work, we show that both the radiation and the absorption losses are significantly reduced in simple nano-scale disk optical resonators incorporating planar indium tin oxide (ITO) electrodes by optimizing the cavity geometry. The disk aspect ratio-disk radius(r) divided by disk height (h)-is considered as the geometric parameter for optimization of the resonator Qfactors.…”

“…However, sub-wavelength (sub-λ) size metallic resonators suffer from low Qfactors in the order of a few hundreds since conventional metallic materials such as gold and silver are extremely lossy in the visible and near-infrared wavelengths. On the other hand, compact optical cavities clad by low-loss transparent conductive oxide (TCO) electrodes are promising for room temperature (RT), continuous-wave (CW), current injection low-threshold micro-lasers due to significantly high Q-factors [3].…”