Versatile, open-access opto-mechanics platform for optical microscopes prototyping

Prototype optical microscopes, built to pursue developments in advanced imaging techniques, need specific optomechanical constructions: preferably with high flexibility in the elements arrangement, easy access to the optical paths, straightforward integration with external optical subsystems - light sources and detectors - as well as good mechanical stability. Typically they are either built around an adapted commercial microscope body or as a home-built setup, based on standard optomechanical elements, and neither solution delivers the desired characteristics. We developed a series of versatile platforms for prototyping optical microscopes in various configurations that use folding mirror(s) to maintain the optical paths horizontal throughout most of the setup, thus enabling the use of standard optical components in the excitation and detection paths and, last but not least, increasing the laser safety of the optical system.Comment: 11 pages, 5 figure

Concept of Inverted Refractive-Index-Contrast Grating Mirror and Exemplary Fabrication by 3D Microprinting

Highly reflective mirrors are indispensable components in a variety of state-of-the-art photonic devices. Typically used, bulky, multi-layered distributed Bragg (DBR) reflectors are limited to lattice-matched semiconductors or nonconductive dielectrics. Here, we introduce an inverted refractive-index-contrast grating (ICG), as compact, single layer alternative to DBR. In the ICG, a subwavelength one-dimensional grating made of a low refractive index material is implemented on a high refractive index cladding. Our numerical simulations show that the ICG provides nearly total optical power reflectance for the light incident from the side of the cladding whenever the refractive index of the grating exceeds 1.75, irrespective of the refractive index of the cladding. Additionally, the ICG enables polarization discrimination and phase tuning of the reflected and transmitted light, the property not achievable with the DBR. We experimentally demonstrate a proof-of-concept ICG fabricated according to the proposed design, using the technique of 3D microprinting in which thin stripes of IP-Dip photoresist are deposited on a Si cladding. This one-step method avoids laborious and often destructive etching-based procedures for grating structuration, making it possible to implement the grating on any arbitrary cladding material

Resonant quenching of Raman scattering due to out-of-plane A1g/A′1 modes in few-layer MoTe2

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Coherent Dynamics of a Single Mn-Doped Quantum Dot Revealed by Four-Wave Mixing Spectroscopy

International audienceFor future quantum technologies the combination of a long quantum state lifetime and an efficient interface with external optical excitation are required. In solids, the former is for example achieved by individual spins, while the latter is found in semiconducting artificial atoms combined with modern photonic structures. One possible combination of the two aspects is reached by doping a single quantum dot, providing a strong excitonic dipole, with a magnetic ion, that incorporates a characteristic spin texture. Here, we perform four-wave mixing spectroscopy to study the system's quantum coherence properties. We characterize the optical properties of the undoped CdT

Resonant quenching of Raman scattering due to out-of-plane A1g/A′1 modes in few-layer MoTe2

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Resonant quenching of Raman scattering due to out-of-plane A1g/A′1 modes in few-layer MoTe2

Temperature-dependent (5 K–300 K) Raman scattering study of A1g/A′1 phonon modes in mono-layer (1L), bilayer (2L), trilayer (3L), and tetralayer (4L) MoTe2 is reported. The temperature evolution of the modes’ intensity critically depends on the flake thickness. In particular with λ=632.8-nm light excitation, a strongly non-monotonic dependence of the A1g mode intensity is observed in 2L MoTe2. The intensity decreases with decreasing temperature down to 220 K, and the A1g mode almost completely vanishes from the Stokes scattering spectrum in the temperature range between 160 K and 220 K. The peak recovers at lower temperatures, and at T=5 K, it becomes three times more intense that at room temperature. Similar non-monotonic intensity evolution is observed for the out-of-plane mode in 3L MoTe2 in which tellurium atoms in all three layers vibrate in-phase. The intensity of the other out-of-plane Raman-active mode (with vibrations of tellurium atoms in the central layer shifted by 180° with respect to the vibrations in outer layers) only weakly depends on temperature. The observed quenching of the Raman scattering in 2L and 3L MoTe2 is attributed to a destructive interference between the resonant and non-resonant contributions to the Raman scattering amplitude. The observed “antiresonance” is related to the electronic excitation at the M point of the Brillouin zone in few-layer MoTe2

Ultra-long-working-distance spectroscopy of single nanostructures with aspherical solid immersion microlenses

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