Thomas Michels

Two-dimensional imaging and modification of nanophotonic resonator modes using a focused ion beam

High-resolution imaging of optical resonator modes is a key step in the development and characterization of nanophotonic devices. Many sub-wavelength mode-imaging techniques have been developed using optical and electron beam excitation-each with its own limitations in spectral and spatial resolution. Here, we report a 2D imaging technique using a pulsed, low-energy focused ion beam of Li+ to probe the near-surface fields inside photonic resonators. The ion beam locally modifies the resonator structure, causing temporally varying spectroscopic shifts of the resonator. We demonstrate this imaging technique on several optical modes of silicon microdisk resonators by rastering the ion beam across the disk surface and extracting the maximum mode shift at the location of each ion pulse. A small shift caused by ion beam heating is also observed and is independently extracted to directly measure the thermal response of the device. This technique enables visualization of the splitting of degenerate modes into spatially-resolved standing waves and permits persistent optical mode editing. Ion beam probing enables minimally perturbative, in operando imaging of nanophotonic devices with high resolution and speed.

Cantilever array with optomechanical read-out and integrated actuation for simultaneous high sensitivity force detection

We present an on-chip cavity optomechanical cantilever array with integrated actuation, that combines high measurement bandwidth and very low displacement noise floor with compactness, robustness, small size, and potential for low cost batch fabrication inherent in micro- electro- mechanical-systems (MEMS).

Optomechanical transducer-based nanocantilever for atomic force microscopy

Reducing cantilever sizes toward the nanoscale enables increased atomic force microscopy (AFM) speed while maintaining high image quality and avoiding sample damage. However downsizing below the optical diffraction limit strongly increases the readout noise to unacceptable levels for conventional far-field beam bouncing detection schemes. Here, we demonstrate fast-scanning AFM imaging with a cavity optomechanical transducer-based nano- cantilever with 2 MHz transduction bandwidth, 4 MHz resonance frequency, sub-picogram mass, 1 N/m stiffness, and 7 fm/Hz½ displacement sensitivity.

Integrated silicon optomechanical transducers and their application in atomic force microscopy

We present integrated optomechanical transducers with exposed tips and demonstrate ultrahigh force sensitivity and large bandwidth. The transducer is implemented as an atomic force microscope probe in the contact mode and nanoscale resolution is demonstrated.