3D-printed miniature spectrometer for the visible range with a 100×100μm^(2) footprint

The miniaturisation of spectroscopic measurement devices opens novel information channels for size critical applications such as endoscopy or consumer electronics.Computational spectrometers in the micrometre size range have been demonstrated,however,these are calibration sensitive and based on complex reconstruction algorithms.Herein we present an angle-insensitive 3D-printed miniature spectrometer with a direct separated spatial-spectral response.The spectrometer was fabricated via two-photon direct laser writing combined with a super-fine inkjet process.It has a volume of less than 100×100×300μm^(3).Its tailored and chirped high-frequency grating enables strongly dispersive behaviour.The miniature spectrometer features a wavelength range of 200 nm in the visible range from 490 nm to 690 nm.It has a spectral resolution of 9.2±1.1 nm at 532 nm and 17.8±1.7 nm at a wavelength of 633 nm.Printing this spectrometer directly onto camera sensors is feasible and can be replicated for use as a macro-pixel of a snapshot hyperspectral camera.

3D printed micro-optics for quantum technology:Optimised coupling of single quantum dot emission into a single-mode fibre

Future quantum technology relies crucially on building quantum networks with high fidelity.To achieve this challenging goal,it is of utmost importance to connect individual quantum systems such that their emitted single photons overlap with the highest possible degree of coherence.This requires perfect mode overlap of the emitted light from different emitters,which necessitates the use of single-mode fibres.Here,we present an advanced manufacturing approach to accomplish this task.We combined 3D printed complex micro-optics,such as hemispherical and Weierstrass solid immersion lenses,as well as total internal reflection solid immersion lenses,on top of individual indium arsenide quantum dots with 3D printed optics on single-mode fibres and compared their key features.We observed a systematic increase in the collection efficiency under variations of the lens geometry from roughly 2 for hemispheric solid immersion lenses up to a maximum of greater than 9 for the total internal reflection geometry.Furthermore,the temperature-induced stress was estimated for these particular lens dimensions and results to be approximately 5 meV.Interestingly,the use of solid immersion lenses further increased the localisation accuracy of the emitters to less than 1 nm when acquiring micro-photoluminescence maps.Furthermore,we show that the single-photon character of the source is preserved after device fabrication,reaching a g^((2))(0)value of approximately 0.19 under pulsed optical excitation.The printed lens device can be further joined with an optical fibre and permanently fixed.This integrated system can be cooled by dipping into liquid helium using a Stirling cryocooler or by a closed-cycle helium cryostat without the necessity for optical windows,as all access is through the integrated single-mode fibre.We identify the ideal optical designs and present experiments that demonstrate excellent high-rate single-photon emission.