Wavelength-scale stationary-wave integrated Fourier-transform spectrometry

Abstract

International audienceSpectrometry is a general physical-analysis approach for investigating light-matter interactions. However, the complex designs of existing spectrometers render them resistant to simplification and miniaturization, both of which are vital for applications in micro- and nanotechnology and which are now undergoing intensive research. Stationary-wave integrated Fourier-transform spectrometry (SWIFTS)-an approach based on direct intensity detection of a standing wave resulting from either reflection (as in the principle of colour photography by Gabriel Lippmann) or counterpropagative interference phenomenon-is expected to be able to overcome this drawback. Here, we present a SWIFTS-based spectrometer relying on an original optical near-field detection method in which optical nanoprobes are used to sample directly the evanescent standing wave in the waveguide. Combined with integrated optics, we report a way of reducing the volume of the spectrometer to a few hundreds of cubic wavelengths. This is the first attempt, using SWIFTS, to produce a very small integrated one-dimensional spectrometer suitable for applications where microspectrometers are essential

Ultradispersive adaptive prism based on a coherently prepared atomic medium

“…Such ultrahigh-frequency dispersion could be used for a compact high spectral resolution spectrometer, similar to compact atomic clocks and magnetometers [29]. The prism has a huge angular dispersion (dθ/dλ = 10 3 nm −1 ), which can spatially resolve spectral widths of a few kilohertz, with a corresponding spectral resolution R = λ/δλ 10 12 (One can see that our approach hold promise; indeed recently, for example, the 1-mm-length spectrometer has shown a resolution of 400 [28]). We have observed the angle of deviation to be an order of magnitude larger than the one previously observed in an inhomogeneous magnetic field [18].…”

Phase closure nulling

“…6. takes advantage of the new developments in integrated optics, permitting both beam recombination and spectrography, thus avoiding the losses at all the diopters of bulk optics used for beam transportation and in the spectrograph. Such a concept, derived from on-going developments for visible spectroscopy (Le Coarer et al 2007) is under investigation ) and can be envision on the sky in the coming few years.…”

CMOS-compatible broadband co-propagative stationary Fourier transform spectrometer integrated on a silicon nitride photonics platform

“…If one compares this expression to what is found in the original SWIFTs design [6], one can find that we are actually stretching the interferogram by a factor of 2n e f f /Δn e f f , which makes the period as large as several tens of micrometers. Consequently, it is now easy to find photodiode arrays that are commercially available and that have a pixel pitch small enough to avoid subsampling of the interferogram.…”

“…Although there exist various miniaturized Fourier transform spectrometers that still involve moving components [3][4][5], it would be better to have an FTS without any moving components. Currently, integrated FTS that are implemented without any moving components can be divided mainly into two categories: the stationary wave integrated FTS (SWIFTs) [6] and the spatial heterodyne spectrometer (SHS) [7].…”

“…On top of the waveguide, nano-scatterers are carefully positioned to couple this interference pattern to a detector array. As introduced in the work of Etienne le Coarer et al [6], the pitch of the interference pattern can be expressed as λ/(2n e f f ) which is much smaller than the pitch size of state-of-the-art photodiode arrays. As a result, the interferogram is subsampled, leading to a limitation on the spectral bandwidth of the FTS.…”