A vacuum ultraviolet laser with a submicrometer spot for spatially resolved photoemission spectroscopy

Yang

et al. 2022

Sci Rep

Focal spot (light spot) at single-photon level have important applications in many fields. This report demonstrates a method for measuring focal spot size at the single-photon level indirectly. This method utilizes Silicon Photomultiplier (SiPM) as the single-photon sensitive detectors, combined with a nano-positioning stage. The approach involves one- or two-dimensional space scanning and a deconvolution operation, which enable evaluations of the size and spatial distribution of the focal spot formed by a single-photon-level pulsed laser. The results indicate that the average full width at half maximum of the focal spot is about 0.657 μm, which is close to the nominal resolution of the objective lens of the microscope (i.e. 0.42 μm). The proposed method has two key advantages: (1) it can measure focal spot at the single-photon level, and (2) the focal spot can easily be aligned with the detector because the array area of the Geiger mode avalanche photodiode (Gm-APD) cells in SiPM is usually on the order of square millimeter, and there is no need to put an optical slit, knife edge, or pinhole in front of the detector. The method described herein is applicable in weak focal spot detection related fields.

Section: Introductionmentioning

confidence: 99%

Measurement of focal light spot at single-photon level with silicon photomultipliers

Yang

et al. 2022

Sci Rep

“…The nonlinear metalens consisting of ZnO meta-atoms not only serves as ultracompact nonlinear medium for VUV light generation but is also capable of effectively focusing the generated harmonic wavefront. Many interesting applications of the reported metalens can be envisioned by integration into current laser-based microscopy systems for biomedical analysis (8), material characterization (4,6), and nanolithography. In light of the design flexibility (45)(46)(47), additional device functionalities can be anticipated, opening the door to new and efficient VUV systems.…”

Section: Discussionmentioning

confidence: 99%

“…Vacuum ultraviolet (VUV) light spans the wavelength range of nominally 100 to 200 nm (6 to 12 eV). VUV radiation is useful for many applications ranging from materials characterization (1)(2)(3)(4)(5)(6) and processing (7) to biotechnology (8,9), due to its high photon energy and strong light-matter interactions. Currently, the lack of low-loss optical components and compact coherent sources is a key limiting factor in the emergence of new applications for light in this wavelength range.…”

Section: Introductionmentioning

confidence: 99%

Vacuum ultraviolet nonlinear metalens

et al. 2022

Vacuum ultraviolet (VUV) light plays an essential role across science and technology, from molecular spectroscopy to nanolithography and biomedical procedures. Realizing nanoscale devices for VUV light generation and control is critical for next-generation VUV sources and systems, but the scarcity of low-loss VUV materials creates a substantial challenge. We demonstrate a metalens that both generates—by second-harmonic generation—and simultaneously focuses the generated VUV light. The metalens consists of 150-nm-thick zinc oxide (ZnO) nanoresonators that convert 394 nm (~3.15 eV) light into focused 197-nm (~6.29 eV) radiation, producing a spot 1.7 μm in diameter with a 21-fold power density enhancement as compared to the wavefront at the metalens surface. The reported metalens is ultracompact and phase-matching free, allowing substantial streamlining of VUV system design and facilitating more advanced applications. This work provides a useful platform for developing low-loss VUV components and increasing the accessibility of the VUV regime.

“…The square ring-shaped photosensitive region is relatively clearly resolved (Figure 3f), which indicates that the FWHM of the light facula should be smaller than 1 μm. The 1D deconvolution results (Figure 4) of the 1D spatial distributions of the PCR of SiPMs (Figure 3) were obtained according to equation (1)(2)(3)(4)(5). It is clear that for each of the tested SiPMs, the spatial distribution range of light facula intensity was on the micron scale, and the intensity distribution of the laser facula closely followed a Bessel distribution.…”

Section: Experimental Setup and Principlementioning

confidence: 95%

Method For Measuring Sub-Micron Facula At Single-Photon Level With Silicon Photomultiplier

Yang

et al. 2021

Preprint

Sub-micron faculae (light spots) at the single-photon level have important applications in many fields. This report demonstrates a method for measuring facula size at the sub-micron single-photon level indirectly. The developed method utilizes Silicon Photomultipliers (SiPMs) as the single-photon response detectors, combined with a nano-positioning stage. The approach involves one- or two-dimensional space scanning and a deconvolution operation, which enable evaluations of the size and spatial distribution of focused facula in a single-photon-level pulsed laser. The results indicate that the average full width at half maximum of the faculae is about 0.66 µm, which is close to the nominal resolution of the objective lens of the microscope (0.42 µm). The proposed method has two key advantages: (1) it can measure sub-micron facula at the single-photon level, and (2) the sub-micron facula can easily be aligned with the detector because the array area of the avalanche photodiode cells in SiPM is usually larger than one square millimeter, and there is no need to put an optical slit, knife edge, or pinhole in front of the detector. The method described herein is applicable in weak light facula detection related fields.