2.5 Photonics and Optoelectronics of 2D Semiconductor TMDCs
41
Fig. 2.13 a Sketch of a circular in-plane distributed-Bragg-reflector-based optical microcavity. b
Atomic-force micrograph and c scanning-electron micrograph of a patterned substrate. e and f show
corresponding cross sections to b and c, respectively. d Two s-SNOM measurements (false-colour
intensity maps) at different probe-laser wavelengths manually combined in one diagram, with the
near-IR wavelength off-resonant with regard to the structure’s design range shown in red (left)
and the in-range green wavelength data displayed in green (right). The white arrow indicates the
central part of the ring system. Remarkably, the profiles show opposite radial intensity modulation,
which is in line with the design considerations. a–f Adapted with permission. [156] Copyright 2019
American Chemical Society
2.5.1 Strong Light–Matter Interaction and Lasing with 2D
Materials
The room-temperature observation of strong light–matter coupling and nonlinearities
in that regime in practical emitter–resonator systems has required the use of largeband-gap materials, which have promised correspondingly high binding energies of
Wannier-Mott excitons [269], or alternatively Frenkel excitons provided by organic
materials, which are strongly localised and naturally deliver a high oscillator strength
[270, 271]. In this context, 2D materials offer a new and unique testbed for light–
matter coupling experiments at elevated temperatures, as pioneering work showed
[64].
The Wave of Hybrid Light–Matter States
The strong interest in TMDCs is explained by their unique properties as nearly perfect quantum wells with exceptionally high binding energies of strongly confined
excitons. This has led to further breakthroughs in this domain, particularly using
tunable and open cavity designs [65, 66, 69] (example shown in Fig. 2.14). Consecutively, many reports followed in an effort to explore this field deeper in recent times
[67, 68, 272]. Up-to-date, different cavity designs have been discussed and different
TMDCs employed, ranging from WS 2 to MoSe 2 [249]. Naturally, these microcavities can be also designed to work with 2D perovskites [273]. While commonly the
Fabry–Pérot-type planar microcavities are used to obtain cavity–polaritons, some
41
Fig. 2.13 a Sketch of a circular in-plane distributed-Bragg-reflector-based optical microcavity. b
Atomic-force micrograph and c scanning-electron micrograph of a patterned substrate. e and f show
corresponding cross sections to b and c, respectively. d Two s-SNOM measurements (false-colour
intensity maps) at different probe-laser wavelengths manually combined in one diagram, with the
near-IR wavelength off-resonant with regard to the structure’s design range shown in red (left)
and the in-range green wavelength data displayed in green (right). The white arrow indicates the
central part of the ring system. Remarkably, the profiles show opposite radial intensity modulation,
which is in line with the design considerations. a–f Adapted with permission. [156] Copyright 2019
American Chemical Society
2.5.1 Strong Light–Matter Interaction and Lasing with 2D
Materials
The room-temperature observation of strong light–matter coupling and nonlinearities
in that regime in practical emitter–resonator systems has required the use of largeband-gap materials, which have promised correspondingly high binding energies of
Wannier-Mott excitons [269], or alternatively Frenkel excitons provided by organic
materials, which are strongly localised and naturally deliver a high oscillator strength
[270, 271]. In this context, 2D materials offer a new and unique testbed for light–
matter coupling experiments at elevated temperatures, as pioneering work showed
[64].
The Wave of Hybrid Light–Matter States
The strong interest in TMDCs is explained by their unique properties as nearly perfect quantum wells with exceptionally high binding energies of strongly confined
excitons. This has led to further breakthroughs in this domain, particularly using
tunable and open cavity designs [65, 66, 69] (example shown in Fig. 2.14). Consecutively, many reports followed in an effort to explore this field deeper in recent times
[67, 68, 272]. Up-to-date, different cavity designs have been discussed and different
TMDCs employed, ranging from WS 2 to MoSe 2 [249]. Naturally, these microcavities can be also designed to work with 2D perovskites [273]. While commonly the
Fabry–Pérot-type planar microcavities are used to obtain cavity–polaritons, some