On‐Chip Measurement of Photoluminescence with High Sensitivity Monolithic Spectrometer

Abstract

Monolithic spectrometer is exceptionally attractive to enable compact, low‐cost spectroscopy for portable sensing and lab‐on‐a‐chip functionality. Unfortunately, simple down‐scaling of the microspectrometer size to the chip‐scale severely weakens light–matter interactions and degrades the sensor performance to unacceptable level. Unlike other state‐of‐the‐art miniature spectral splitting filters or photonic structures, bandgap‐graded nanowire strongly enhances the light‐matter interaction, which is a highly demanded yet unfulfilled feature for high‐precision on‐chip sensing. Here, on‐chip measurement of photoluminescence by a monolithic spectrometer made of a single composition‐graded CdSxSe1–x nanowire is reported. The nanowire is engineered to a waveguide‐mode‐operated, dispersive photodiode array. It works as a monolithic spectrometer chip with strong light–matter interaction and superior noise figure. On‐chip measurement of single‐point photoluminescence signals with 1013 Jones room‐temperature detectivity and 5 nm spectral resolution is illustrated. This demonstration of a compact, low‐cost, and high‐performance miniature spectrometer marks a major step towards on‐chip spectroscopy for fine resolution and sensitive detection.

3D-printed miniature spectrometer for the visible range with a 100 × 100 μm² footprint

“…Furthermore, the implementation of a spectrometer fabricated strictly by 3D printing can be highlighted as a novelty. The measured ratio of bandwidth per resolution of is in a margin similar to those of other spectrometers that have been demonstrated in this size range 29,31 . In the category of direct spectrometers, the microspectrometer presented here is the first of its kind in this size range (see Fig.…”

“…Therefore, an array of slightly different spectrometers could be fabricated, with each being optimised for another part of the spectrum. This is a major advantage with regard to spectrometers fabricated using non-classical approaches, such as colloidal quantum dots 27 , photonic crystal slabs 28 , nanowires 29 , and disordered photonic structures 31 . These methods have either a rather small bandwidth or cannot be intrinsically extended to the infrared region.…”

“…It is our understanding that only two spectrometers have been demonstrated in which the system sizes are of the same order of magnitude as our footprint of 100 × 100 μm 2 . They are based on nanowires 29,30 or disordered photonic structures 31 , and they have a bandwidth per resolution ratio that is similar to the one in our approach. However, owing to wavelength multiplexing, the system must be calibrated with an iterative reconstruction algorithm to deduce the original spectrum.…”

Miniaturization of optical spectrometers

“…This increases the complexity of manufacturing and limits miniaturization. Recently, spectral responsivity engineered nanostructure has been demonstrated to integrate both these functions (13,(86)(87)(88)(89)(90) as shown in Figs. 5I and J.…”

Miniaturized Multispectral Detector Derived from Gradient Response Units on Single MAPbX3 Microwire

“…[ 24 ] Hence, the facile preparation process for fabricating miniaturized high‐performance chip‐level multispectral detectors with broad response is desired. [ 25 ]…”