Fig. 13. (a) Schematic geometry of a bottom-contact/top gate light emitting field-effect transistor integrated into an optical cavity. (b) Angle- and spectrally resolved reflectivity (left), photoluminescence (middle) and electroluminescence (right) of the channel area in the device. The emission from both the photoluminescence and electroluminescence agrees with the reflectivity spectra and can be fitted well using a coupled oscillator model. Reproduced from ref. 255 with permission from Springer Nature, copyright 2017. (c) The polarization-dependent absorption spectra of an aligned SWCNT film, showing the first and second interband exciton peaks, E₁₁ and E₂₂. (d) Experimental transmittance spectra at zero detuning for various polarization angles (from 0° to 90°) for a device working in the E₁₁ region using SWCNT films having different thicknesses (d). Reproduced from ref. 58 with permission from Springer Nature, copyright 2018. (e) Dispersion relation extracted from the angle-resolved reflectivity spectra of the cavity based on the MoS₂ monolayer. The two black solid curves correspond to theoretical fits of the polariton branches using a coupled oscillator model. Reproduced from ref. 261 with permission from Springer Nature, copyright 2015. (f) Schematic showing the valley-dependent optical selection rules at inequivalent K and K′ valleys at the edges of the Brillouin zone. (g) Emission polarization for bare excitons (MoS₂ excitons), upper polariton (UP) and lower polariton (LP) branches as a function of temperature. Reproduced from ref. 271 with permission from Springer Nature, copyright 2017.