The potential for improving the penetration depth of optical coherence tomography systems by using light sources with longer wavelengths has been known since the inception of the technique in the early 1990s.Neverthel...The potential for improving the penetration depth of optical coherence tomography systems by using light sources with longer wavelengths has been known since the inception of the technique in the early 1990s.Nevertheless,the development of mid-infrared optical coherence tomography has long been challenged by the maturity and fidelity of optical components in this spectral region,resulting in slow acquisition,low sensitivity,and poor axial resolution.In this work,a mid-infrared spectral-domain optical coherence tomography system operating at a central wavelength of 4μm and an axial resolution of 8.6μm is demonstrated.The system produces two-dimensional cross-sectional images in real time enabled by a high-brightness 0.9-to 4.7-μm mid-infrared supercontinuum source with a pulse repetition rate of 1 MHz for illumination and broadband upconversion of more than 1-μm bandwidth from 3.58–4.63μm to 820–865 nm,where a standard 800-nm spectrometer can be used for fast detection.The images produced by the mid-infrared system are compared with those delivered by a state-of-the-art ultra-high-resolution near-infrared optical coherence tomography system operating at 1.3μm,and the potential applications and samples suited for this technology are discussed.In doing so,the first practical mid-infrared optical coherence tomography system is demonstrated,with immediate applications in real-time non-destructive testing for the inspection of defects and thickness measurements in samples that exhibit strong scattering at shorter wavelengths.展开更多
Thermal nanoimprinting is a fast and versatile method for transferring the anti-reflective properties of subwavelength nanostructures onto the surface of highly reflective substrates, such as chalcogenide glass optica...Thermal nanoimprinting is a fast and versatile method for transferring the anti-reflective properties of subwavelength nanostructures onto the surface of highly reflective substrates, such as chalcogenide glass optical fiber end faces. In this paper, the technique is explored experimentally on a range of different types of commercial and custom-drawn optical fibers to evaluate the influence of geometric design, core/cladding material, and thermo-mechanical properties. Up to32.4% increased transmission and 88.3% total transmission are demonstrated in the 2–4.3 μm band using a mid-infrared(IR) supercontinuum laser.展开更多
Controlling neuronal activity using implantable neural interfaces constitutes an important tool to understand and develop novel strategies against brain diseases.Infrared neurostimulation is a promising alternative to...Controlling neuronal activity using implantable neural interfaces constitutes an important tool to understand and develop novel strategies against brain diseases.Infrared neurostimulation is a promising alternative to optogenetics for controlling the neuronal circuitry with high spatial resolution.However,bi-directional interfaces capable of simultaneously delivering infrared light and recording electrical signals from the brain with minimal inflammation have not yet been reported.Here,we have developed a soft fibre-based device using high-performance polymers which are>100-fold softer than conventional silica glass used in standard optical fibres.The developed implant is capable of stimulating the brain activity in localized cortical domains by delivering laser pulses in the 2μm spectral region while recording electrophysiological signals.Action and local field potentials were recorded in vivo from the motor cortex and hippocampus in acute and chronic settings,respectively.Immunohistochemical analysis of the brain tissue indicated insignificant inflammatory response to the infrared pulses while the signal-to-noise ratio of recordings still remained high.Our neural interface constitutes a step forward in expanding infrared neurostimulation as a versatile approach for fundamental research and clinically translatable therapies.展开更多
基金the financial support from Innovation Fund Denmark through ShapeOCT Grant No.4107-00011Athe NIHR Biomedical Research Center at Moorfields Eye Hospital NHS Foundation Trust+3 种基金the UCL Institute of Ophthalmologythe Royal Society Wolfson Research Merit Award.the support from H.C.Orsted COFUNDED Marie-Curie action fellowshipfinancial support from H.C.Orsted for the running cost.
文摘The potential for improving the penetration depth of optical coherence tomography systems by using light sources with longer wavelengths has been known since the inception of the technique in the early 1990s.Nevertheless,the development of mid-infrared optical coherence tomography has long been challenged by the maturity and fidelity of optical components in this spectral region,resulting in slow acquisition,low sensitivity,and poor axial resolution.In this work,a mid-infrared spectral-domain optical coherence tomography system operating at a central wavelength of 4μm and an axial resolution of 8.6μm is demonstrated.The system produces two-dimensional cross-sectional images in real time enabled by a high-brightness 0.9-to 4.7-μm mid-infrared supercontinuum source with a pulse repetition rate of 1 MHz for illumination and broadband upconversion of more than 1-μm bandwidth from 3.58–4.63μm to 820–865 nm,where a standard 800-nm spectrometer can be used for fast detection.The images produced by the mid-infrared system are compared with those delivered by a state-of-the-art ultra-high-resolution near-infrared optical coherence tomography system operating at 1.3μm,and the potential applications and samples suited for this technology are discussed.In doing so,the first practical mid-infrared optical coherence tomography system is demonstrated,with immediate applications in real-time non-destructive testing for the inspection of defects and thickness measurements in samples that exhibit strong scattering at shorter wavelengths.
基金supported by the European Commission (Nos. 317803, 722380, and 732968)the Innovation Fund Denmark (No. 4107-00011A)+2 种基金the Danish Maritime Fund (No. 2019-137)the Lundbeck Foundation (No. R276-2018869)the Independent Research Fund Denmark (No. 8022-00091B)。
文摘Thermal nanoimprinting is a fast and versatile method for transferring the anti-reflective properties of subwavelength nanostructures onto the surface of highly reflective substrates, such as chalcogenide glass optical fiber end faces. In this paper, the technique is explored experimentally on a range of different types of commercial and custom-drawn optical fibers to evaluate the influence of geometric design, core/cladding material, and thermo-mechanical properties. Up to32.4% increased transmission and 88.3% total transmission are demonstrated in the 2–4.3 μm band using a mid-infrared(IR) supercontinuum laser.
基金We thank Yuki Mori,Palle Koch and Ryszard S.Gomolka from Panum NMR Core Facility for their technical support.We also thank Guanghui Li from the Department of Neuroscience at Copenhagen University,as well as Ole Bang and Yazhou Wang from the Department of Electrical and Photonics Engineering at the Technical University of Denmark,for providing their expertise and support during the study.This research has been financially supported by Lundbeck Fonden projects(Multi-BRAIN,R276-2018-869 and R380-2021-1171)and VILLUM FONDEN(36063).
文摘Controlling neuronal activity using implantable neural interfaces constitutes an important tool to understand and develop novel strategies against brain diseases.Infrared neurostimulation is a promising alternative to optogenetics for controlling the neuronal circuitry with high spatial resolution.However,bi-directional interfaces capable of simultaneously delivering infrared light and recording electrical signals from the brain with minimal inflammation have not yet been reported.Here,we have developed a soft fibre-based device using high-performance polymers which are>100-fold softer than conventional silica glass used in standard optical fibres.The developed implant is capable of stimulating the brain activity in localized cortical domains by delivering laser pulses in the 2μm spectral region while recording electrophysiological signals.Action and local field potentials were recorded in vivo from the motor cortex and hippocampus in acute and chronic settings,respectively.Immunohistochemical analysis of the brain tissue indicated insignificant inflammatory response to the infrared pulses while the signal-to-noise ratio of recordings still remained high.Our neural interface constitutes a step forward in expanding infrared neurostimulation as a versatile approach for fundamental research and clinically translatable therapies.
