scholarly journals Manipulating and measuring single atoms in the Maltese cross geometry

2021 ◽  
Vol 1 ◽  
pp. 102
Author(s):  
Lorena C. Bianchet ◽  
Natalia Alves ◽  
Laura Zarraoa ◽  
Natalia Bruno ◽  
Morgan W. Mitchell
Keyword(s):  
Collection Efficiency ◽  
Coupling Efficiency ◽  
Numerical Aperture ◽  
Single Mode ◽  
Optical Systems ◽  
Single Atom ◽  
Trapped Atoms ◽  
Atom Trap ◽  
Trap Axis ◽  
Maltese Cross

Background: Optical microtraps at the focus of high numerical aperture (high-NA) imaging systems enable efficient collection, trapping, detection and manipulation of individual neutral atoms for quantum technology and studies of optical physics associated with super- and sub-radiant states.  The recently developed “Maltese cross” geometry (MCG) atom trap uses four in-vacuum lenses to achieve four-directional high-NA optical coupling to single trapped atoms and small atomic arrays. This article presents the first extensive characterisation of atomic behaviour in a MCG atom trap. Methods: We employ a MCG system optimised for high coupling efficiency and characterise the resulting properties of the trap and trapped atoms.  Using current best practices, we measure occupancy, loading rate, lifetime, temperature, fluorescence anti-bunching and trap frequencies. We also use the four-directional access to implement a new method to map the spatial distribution of collection efficiency from high-NA optics:  we use the two on-trap-axis lenses to produce a 1D optical lattice, the sites of which are stochastically filled and emptied by the trap loading process. The two off-trap-axis lenses are used for imaging and single-mode collection.  Correlations of single-mode and imaging fluorescence signals are then used to map the single-mode collection efficiency. Results: We observe trap characteristics comparable to what has been reported for single-atom traps with one- or two-lens optical systems. The collection efficiency distribution in the axial and transverse directions is directly observed to be in agreement with expected collection efficiency distribution from Gaussian beam optics. Conclusions: The multi-directional high-NA access provided by the Maltese cross geometry enables complex manipulations and measurements not possible in geometries  with fewer  directions of  access,  and can  be  achieved  while  preserving other trap characteristics such as lifetime, temperature, and trap size.

Fabrication of Eyeball-Like Spherical Micro-Lens Array for Optical Fiber Coupling

2009 ◽  
Author(s):  
S. C. Shen ◽  
C. T. Pan ◽  
R. F. Shyu ◽  
C. H. Chao ◽  
J. C. Huang ◽  
...  
Keyword(s):  
Silicon Wafer ◽  
Substrate Surface ◽  
Coupling Efficiency ◽  
Numerical Aperture ◽  
Spherical Geometry ◽  
Single Mode ◽  
Batch Process ◽  
Optical Measurements ◽  
Lens Array ◽  
Micro Lens

Batch-fabrication of eyeball-like spherical micro-lens not only reduces micro assembly cost, but also replaces conventional ball-lenses or costly GRINs (Gradient Reflective Index) without sacrificing performance. Compared to the conventional micro-lenses made in a half-spherical geometry, the eyeball-like micro-lens is a sphere, which allows focusing light in all directions on the substrate surface, thus providing application flexibility for optical applications. The current eyeball-like spherical micro-lens is made using photoresist SU-8. This work develops a batch process at low temperature by spin-coating SU-8 on a surface of silicon wafer. The SU-8 thick film is patterned by UV lithography to form an array of holes for holding eyeball-like spherical micro-lens. The fabrication process employs bulk micromachining to fabricate an array of nozzles on the silicon wafer. Next, this process pours viscous SU-8 into the cavity of silicon wafer and presses it through the nozzle before reflow. The eyeball-like spherical micro-balls form by balancing between surface tension and cohesion. Varying the amount of SU-8 pressed through the nozzle controls the diameter of the balls. This paper designs a pattern with a 3 × 3 lens-array with a numerical aperture of about 0.38. Diameters range from 60 to 500 um. Optical measurements indicate a diameter fluctuation within 3% and an optical insertion loss is below 2.5dB with a wavelength of 635nm in a single-mode fiber (SMF). Therefore the eyeball-like spherical micro-lens is capable of increasing coupling efficiency.

scholarly journals A Miniature Fibre-Optic Raman Probe Fabricated by Ultrafast Laser-Assisted Etching

Micromachines ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 185
Author(s):  
Calum A. Ross ◽  
David G. MacLachlan ◽  
Brian J. E. Smith ◽  
Rainer J. Beck ◽  
Jonathan D. Shephard ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Collection Efficiency ◽  
Surgical Techniques ◽  
Numerical Aperture ◽  
Ultrafast Laser ◽  
The Body ◽  
Optical Biopsy ◽  
Optical Systems ◽  
Direct Laser ◽  
Raman Probe

Optical biopsy describes a range of medical procedures in which light is used to investigate disease in the body, often in hard-to-reach regions via optical fibres. Optical biopsies can reveal a multitude of diagnostic information to aid therapeutic diagnosis and treatment with higher specificity and shorter delay than traditional surgical techniques. One specific type of optical biopsy relies on Raman spectroscopy to differentiate tissue types at the molecular level and has been used successfully to stage cancer. However, complex micro-optical systems are usually needed at the distal end to optimise the signal-to-noise properties of the Raman signal collected. Manufacturing these devices, particularly in a way suitable for large scale adoption, remains a critical challenge. In this paper, we describe a novel fibre-fed micro-optic system designed for efficient signal delivery and collection during a Raman spectroscopy-based optical biopsy. Crucially, we fabricate the device using a direct-laser-writing technique known as ultrafast laser-assisted etching which is scalable and allows components to be aligned passively. The Raman probe has a sub-millimetre diameter and offers confocal signal collection with 71.3% ± 1.5% collection efficiency over a 0.8 numerical aperture. Proof of concept spectral measurements were performed on mouse intestinal tissue and compared with results obtained using a commercial Raman microscope.

scholarly journals A Miniature Fibre-optic Raman Probe Fabricated by Ultrafast Laser Assisted Etching

2020 ◽  
Author(s):  
Calum A. Ross ◽  
David G. MacLachlan ◽  
Brian Smith ◽  
Rainer J. Beck ◽  
Jonathan D. Shephard ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Collection Efficiency ◽  
Surgical Techniques ◽  
Numerical Aperture ◽  
Ultrafast Laser ◽  
The Body ◽  
Optical Biopsy ◽  
Optical Systems ◽  
Direct Laser ◽  
Raman Probe

Optical biopsy describes a range of medical procedures in which light is used to investigate disease in the body, often in hard-to-reach regions via optical fibres. Optical biopsies can reveal a multitude of diagnostic information to aid therapeutic diagnosis and treatment with higher specificity and shorter delay than traditional surgical techniques. One specific type of optical biopsy relies on Raman spectroscopy to differentiate tissue types at the molecular level and has been used successfully to stage cancer. However, complex micro-optical systems are usually needed at the distal-end to optimise the signal-to-noise properties of the Raman signal collected. Manufacturing these devices remains a critical challenge, particularly in a way suitable for large scale adoption. In this paper, we describe a novel fibre-fed micro-optic system designed for efficient signal delivery and collection during a Raman spectroscopy based optical biopsy. Crucially, we fabricate the device using a direct-laser-writing technique known as ultrafast laser assisted etching which is scalable and allows components to be aligned passively. The Raman probe has a sub-millimetre diameter and offers confocal signal collection with 71.3 ± 1.5% collection efficiency over a 0.8 numerical aperture. Proof of concept spectral measurements were performed on mouse intestinal tissue and compared with results obtained using a commercial Raman microscope.

Coupling efficiency and sensitivity of an LED to a single-mode fibre

1986 ◽  
Vol 22 (21) ◽  
pp. 1110 ◽  
Author(s):  
D.N. Christodoulides ◽  
L.A. Reith ◽  
M.A. Saifi
Keyword(s):  
Coupling Efficiency ◽  
Single Mode ◽  
Single Mode Fibre ◽  
Mode Fibre

scholarly journals In-Line Analysis of Diffusion Processes in Micro Channels by Long Distance Raman Photometric Measurement Technology—A Proof of Concept Study

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 116
Author(s):  
Julian Deuerling ◽  
Shaun Keck ◽  
Inasya Moelyadi ◽  
Jens-Uwe Repke ◽  
Matthias Rädle
Keyword(s):  
Numerical Aperture ◽  
Spot Size ◽  
Measuring System ◽  
Optical Systems ◽  
Measurement Technology ◽  
Long Distance ◽  
Measuring Point ◽  
Acetone Concentration ◽  
Micro Channels ◽  
Set Up

This work presents a novel method for the non-invasive, in-line monitoring of mixing processes in microchannels using the Raman photometric technique. The measuring set-up distinguishes itself from other works in this field by utilizing recent state-of-the-art customized photon multiplier (CPM) detectors, bypassing the use of a spectrometer. This addresses the limiting factor of integration times by achieving measuring rates of 10 ms. The method was validated using the ternary system of toluene–water–acetone. The optical measuring system consists of two functional units: the coaxial Raman probe optimized for excitation at a laser wavelength of 532 nm and the photometric detector centered around the CPMs. The spot size of the focused laser is a defining factor of the spatial resolution of the set-up. The depth of focus is measured at approx. 85 µm with a spot size of approx. 45 µm, while still maintaining a relatively high numerical aperture of 0.42, the latter of which is also critical for coaxial detection of inelastically scattered photons. The working distance in this set-up is 20 mm. The microchannel is a T-junction mixer with a square cross section of 500 by 500 µm, a hydraulic diameter of 500 µm and 70 mm channel length. The extraction of acetone from toluene into water is tracked at an initial concentration of 25% as a function of flow rate and accordingly residence time. The investigated flow rates ranged from 0.1 mL/min to 0.006 mL/min. The residence times from the T-junction to the measuring point varies from 1.5 to 25 s. At 0.006 mL/min a constant acetone concentration of approx. 12.6% was measured, indicating that the mixing process reached the equilibrium of the system at approx. 12.5%. For prototype benchmarking, comparative measurements were carried out with a commercially available Raman spectrometer (RXN1, Kaiser Optical Systems, Ann Arbor, MI, USA). Count rates of the spectrophotometer surpassed those of the spectrometer by at least one order of magnitude at identical target concentrations and optical power output. The experimental data demonstrate the suitability and potential of the new measuring system to detect locally and time-resolved concentration profiles in moving fluids while avoiding external influence.

scholarly journals Ultrawide-angle and high-efficiency metalens in hexagonal arrangement

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Chun-Yuan Fan ◽  
Chia-Ping Lin ◽  
Guo-Dung J. Su
Keyword(s):  
High Efficiency ◽  
Numerical Aperture ◽  
Vital Role ◽  
Optical Systems ◽  
Wide Field ◽  
Wide Angle ◽  
Camera Systems ◽  
Single Lens ◽  
Hexagonal Arrangement ◽  
Virtual And Augmented Reality

Abstract Wide-angle optical systems play a vital role in imaging applications and have been researched for many years. In traditional lenses, attaining a wide field of view (FOV) by using a single optical component is difficult because these lenses have crucial aberrations. In this study, we developed a wide-angle metalens with a numerical aperture of 0.25 that provided a diffraction-limited FOV of over 170° for a wavelength of 532 nm without the need for image stitching or multiple lenses. The designed wide-angle metalens is free of aberration and polarization, and its full width of half maximum is close to the diffraction limit at all angles. Moreover, the metalens which is designed through a hexagonal arrangement exhibits higher focusing efficiency at all angles than most-seen square arrangement. The focusing efficiencies are as high as 82% at a normal incident and 45% at an incident of 85°. Compared with traditional optical components, the proposed metalens exhibits higher FOV and provides a more satisfactory image quality because of aberration correction. Because of the advantages of the proposed metalens, which are difficult to achieve for a traditional single lens, it has the potential to be applied in camera systems and virtual and augmented reality.

Fabrication of Lensed Plastic Optical Fiber Array Using Electrostatic Force

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Yih-Tun Tseng ◽  
Jhong-Bin Huang ◽  
Che-Hsin Lin ◽  
Chin-Lung Chen ◽  
Wood-Hi Cheng
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Electrostatic Force ◽  
Coupling Efficiency ◽  
Numerical Aperture ◽  
Uv Curing ◽  
Power Budget ◽  
Fiber Array ◽  
Plastic Optical Fibers ◽  
Efficient Coupling

The GI (graded-index) POFs (Plastic optical fibers), which has been proven to reach distances as long as 1 km at 1.25 Gb/s has a relatively low numerical aperture . Therefore, the efficient coupling of GI POFs to the light source has become critical to the power budget in the system. Efficient coupling for a POFs system normally involves either a separate lens or the direct formation of the lens at the end of the fiber. Forming the lens-like structure directly on the fiber end is preferred for simplicity of fabrication and packaging, such as polishing and fusion, combine different fibers with the cascaded fiber method and hydroflouride (HF) chemical etching. These approaches are well established, but applicable only to glass. Optical assembly architecture for multichannel fibers and optical devices is critical to optical fiber interconnections. Multichannel fiber-pigtail laser diode (LD) modules have potential for supporting higher data throughput and longer transmission distances. However, to be of practical use, these modules must be more precise. This work proposes and manufactures lensed plastic optical fibers (LPOF) array. This novel manipulation can be utilized to fabricate an aspherical lens on a fiber array after the UV curing of the photo-sensitive polymer; the coupling efficiency (CE) is increased and exceeds 47% between the LD array and the fiber array.

Transmission Electron Microscopy Imaging of Structural Transformation Dynamics in a Single Nanocrystal

2012 ◽  
Vol 20 (1) ◽  
pp. 18-22
Author(s):  
Haimei Zheng
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Collection Efficiency ◽  
Single Atom ◽  
Microscopy Imaging ◽  
High Brightness ◽  
Rapid Acquisition ◽  
Signal Collection ◽  
Transmission Electron ◽  
Resolution Imaging

Over the last decade, transmission electron microscopy (TEM) has advanced remarkably. With the development of aberration-corrected optics, improved recording systems, high brightness guns, and so on, imaging with single-atom sensitivity across the periodic table has become a reality. Atomic resolution imaging with rapid acquisition and with greater signal collection efficiency opens many opportunities in the study of dynamic processes of materials.

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