Interactions with a photonic crystal micro-cavity using AFM in contact or tapping mode operation

In this paper we show how the evanescent field of a localized mode in a photonic crystal micro-cavity can be perturbed by a nano-sized AFM tip. Due to the high field intensities in the cavity, we can see a significant change in output power when the tip is brought into the evanescent field in either contact or tapping mode operation. We find a 4 dB modulation, when using a $Si_{3}N_{4}$ tip and we show that the transmittance can be tuned from 0.32 to 0.8 by varying the average tapping height

Nano-mechanical tuning and imaging of a photonic crystal micro-cavity resonance

We show that nano-mechanical interaction using atomic force microscopy (AFM) can be used to map out mode-patterns of an optical micro-resonator with high spatial accuracy. Furthermore we demonstrate how the Q-factor and center wavelength of such resonances can be sensitively modified by both horizontal and vertical displacement of an AFM tip consisting of either Si3N4 or Si material. With a silicon tip we are able to tune the resonance wavelength by 2.3 nm, and to set Q between values of 615 and zero, by expedient positioning of the AFM tip. We find full on/off switching for less than 100 nm vertical, and for 500 nm lateral\ud displacement at the strongest resonance antinode locations

Modeling and experimental verification of the dynamic interaction of an AFM-tip with a photonic crystal microcavity

We present a transmission model for estimating the effect of the atomic-force microscopy tapping tip height on a photonic crystal microcavity (MC). This model uses a fit of the measured tip-height-dependent transmission above a “hot spot” in the MC. The predicted transmission versus average tapping height is in good agreement with the values obtained from tapping mode experiments. Furthermore, we show that for the existing, nonoptimized structure, the transmission coefficient can be tuned between 0.32 and 0.8 by varying the average tapping height from 26 to 265 nm. A transmission larger than that of the undisturbed cavity at resonance was observed at specific tip locations just outside the cavity-terminating holes

Grated waveguide cavity for label-free protein and mechano-optical gas sensing

We demonstrate the versatility of a silicon nitride grated waveguide optical cavity as compact integrated optical sensors for (bulk) concentration detection, label-free protein sensing, and – with an integrated cantilever suspended above it – gas sensing

Evanescent-field intra-cavity sensing with a dual-wavelength distributed-feedback laser

We demonstrate an integrated optical particle sensor based on a dual-wavelength distributed-feedback waveguide laser. Micro-particles were detected down to a size of 1 μm, which represents the typical size of many fungal and bacterial pathogens