Imaging nanophotonic modes of microresonators using a focused ion beam

Abstract

Optical microresonators have proven powerful in a wide range of applications, including cavity quantum electrodynamics1–3, biosensing4, microfludics5, and cavity optomechanics6–8. Their performance depends critically on the exact distribution of optical energy, confined and shaped by the nanoscale device geometry. Near-field optical probes9 can image this distribution, but the physical probe necessarily perturbs the near field, which is particularly problematic for sensitive high quality factor resonances10,11. We present a new approach to mapping nanophotonic modes that uses a controllably small and local optomechanical perturbation introduced by a focused lithium ion beam12. An ion beam (radius ≈50 nm) induces a picometer-scale dynamic deformation of the resonator surface, which we detect through a shift in the optical resonance wavelength. We map five modes of a silicon microdisk resonator (Q≥20,000) with both high spatial and spectral resolution. Our technique also enables in-situ observation of ion implantation damage and relaxation dynamics in a silicon lattice13,14.

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

“…Recently, focused ion beams (FIB) have been introduced as a promising alternative for in operando measurement of nanophotonic resonator modes [31] with nanometer-scale resolution. As with NSOM and PMS, a specific mode is selected for imaging by tuning an external excitiation laser, and the spectral resolution is limited only by shot noise in photodetection of the resonance excitation.…”

Cold-Atom Ion Sources for Focused Ion Beam Applications

“…A lithium ion microscope has been constructed using a magneto-optical trap ion source (MOTIS), and a number of applications have been demonstrated with this instrument. Low energy ion microscopy reveals new imaging modalities [7], lithiation of battery materials is studied on the nanoscale [8], and mode distributions in optical microdisk resonators are visualized with great detail [9]. Very recently, a cold atomic beam-based low temperature ion source (LoTIS) has been realized, where measurements show a brightness as high as 1.3 x10 7 A m -2 sr -1 eV -1 -a factor of 13 higher than the Ga + LMIS brightness of 1 x10 6 A m -2 sr -1 eV -1 .…”

Optical far-field super-resolution microscopy using nitrogen vacancy center ensemble in bulk diamond

“…Recently, several different types of optical nanoscopy methods for NV center imaging have been developed [21][22][23][24][25][26][27] . Therefore, it is possible to use NV center ensemble arrays as probes to realize sub-diffraction spatial resolution quantum sensing.In particular, the local optical field detection with high spatial resolution is interesting in diverse fields ranging from nanophotonics to biosensing 4,14,15 . In this work, we demonstrate the local optical field detection with subdiffraction resolution using NV center ensemble in bulk diamond as probes, as shown in Fig.…”

“…Typically, it is realized by scanning a specially prepared tip with attached nanodiamond 4,5,[11][12][13] . However, the presence and movement of tips may change the local field distribution at the nanoscale 14,15 . Additionally, the preparation of the tips is usually difficult 16 .…”

“…In particular, the local optical field detection with high spatial resolution is interesting in diverse fields ranging from nanophotonics to biosensing 4,14,15 . In this work, we demonstrate the local optical field detection with subdiffraction resolution using NV center ensemble in bulk diamond as probes, as shown in Fig.…”