Tip enhanced photoluminesence imaging of waveguide-mode-coupled infrared quantum dot emission

Waveguide modes are a ubiquitous manifestation of total internal reflection in high index dielectrics. Scanning near field optical microscopy reveals their long propagation distance (low loss) particularly in the short wave infrared range (SWI, 1000-2000) nm, while shorter wavelengths become lossy due to band edge absorption. Although these sub-diffractional excitations offer enhanced emission, they are inaccessible in conventional diffraction-limited microscopies. Here, using tip-enhanced photoluminesence (nano-PL), we study infrared PbS quantum dots coupled to bulk MoS2 waveguide modes. The magnitude of the emission enhancement peaks around 900-1000 nm excitation wavelengths. This suggests that SWI-range nano-PL offers superior performance to vis-range emitters when coupled to TMD waveguides. This work highlights the promise of the infrared range for coupling emitters to confined light-matter excitations.