FRONTIERS ARTICLEHot Brownian thermometry and cavity-enhanced harmonic generation with nonlinear optical nanowires

- Fabry-Pérot resonances are observed to affect SHG for KNbO3 (KN) nanowires (NWs).
- Laser trapping shows temperature >40 °C during hot Brownian motion of KNbO3 NW's SHG.
- Continuous-wave sum-frequency generation is demonstrated for optically trapped KN NWs.

The non-linear response of nanoscale materials is affected by phase-matching conditions that are critically dependent on temperature. It has remained a persistent challenge to measure the temperature of individual nonlinear optical nanostructures in situ. Here, we measure the temperature of individual KNbO3 nanowires in an optical trap through analysis of the Brownian dynamics. Additionally, we show Fabry-Pérot-type cavity enhancement of second harmonic generation in one-dimensional potassium niobate nanowires (KNNW) using a tunable, continuous wave (CW), near-infrared (NIR) trapping laser. A second co-aligned CW NIR laser is used to extend the range of visible emission through sum frequency generation.

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