Angle-Resolved Cathodoluminescence Imaging Spectroscopy (ARCIS)

A new microscopy technique

Our group has developed a unique cathodoluminescence spectroscopy instrument that enables the study of nanostructures with deep-subwavelength optical resolution. The instrument uses a 5-30 keV electron beam in a SEM to excite nanophotonic structures, while the emitted light is collected by a parabolic mirror placed between the sample and the microscope’s electron column. A commercial version of the instrument has been brought on the market in 2014 by Delmic. In 2014, the ARCIS instrument was awarded the MRS Materials Innovation and Characterization Award. It was also highlighed in Nature 493, 143 (2013) and Microscopy Today 24, 12 (2016).

Spectral analysis: measuring the local optical density of states

The collected radiation is spectrally analyzed for every electron beam position, so that a two-dimensional emission map can be recorded. This map is related to the local optical density of states (LDOS) and can be determined with a spatial accuracy down to 3 nm in the 400-1700 nm spectral range.

Angular measurements: momentum spectroscopy

An imaging CCD camera records the beam profile emanating from the mirror. From this profile the angle-resolved radiation pattern from the sample can be derived, enabling “momentum spectroscopy”, measuring the in-plane wave vector of light at every frequency and position. Using this technique the local bandstructure of periodic and aperiodic structures can be determined with a spatial resolution of 10 nm.


Using a linear polarizer and a quarter-wave plate, 4 independent polarization-resolved measurements are done from which the full set of Stokes parameters is derived. This enables identification of the degree of linearly and circularly polarized light emitted from the sample. These measurements can be done in spatial, spectral and angle-resolved mode.

Time resolved measurements: beam blanker and femtosecond-laser-driven cathode

The newest design, made on a new FEI Quanta 650 SEM, adds time-resolved detection capabilities to the microscope. Using an electrostatic beam blanker, electron pulses shorter than 30 ps can be made, and the statistics of the emitted cathodoluminescence is recorded using single-photon counting and correlation spectroscopy. This enables nanometer-resolution lifetime imaging, studies of (anti-)bunching of single quantum emitters, and much more. In second design, that has just become operational, the electron cathode of an Quanta250 SEM is driven by 250-fs UV laser pulses to create picosecond electron pulses, enabling ultrafast pump-probe cathodoluminescence imaging spectroscopy, as we have recently demonstrated. For details, see our recent paper in Ultramicroscopy.

Table-top CL microscope

Most recently, in a joint project with Delmic, funded by an ERC Proof-of-concept grant, we have used a Phenom World table-top SEM to develop a table-top CL microscope. We have developed two complementary geometries, using either a lensed fiber or a parabolic mirror to collect the CL emission. A spectrometer is integrated with the table-top SEM-CL system and analyses the emission. Clear spectra and CL maps are observed from samples relevant in geology and semiconductor applications. A technical summary appeared in Microscopy and Analysis.


CL team at the Millikan pond at the campus of Caltech (May 2017)

ARCIS publications