Pub Date : 2019-10-17DOI: 10.1109/CLEOE-EQEC.2019.8871530
F. Galeotti, I. S. Vollenbroek, M. Petruzzella, F. Pagliano, F. V. van Otten, Ž. Zobenica, H. S. Marnani, A. Mohtashami, R. W. van der Heijden, A. Fiore
A nano-opto-electro-mechanical transducer for displacement sensing is presented. It consists of a double-membrane photonic crystal cavity integrated with electro-optical read-out and on-chip light-delivery. The operation is demonstrated by atomic force microscope actuation and photocurrent sensing.
{"title":"On-Chip Photocurrent Displacement Sensor Based on a Waveguide-Coupled Nanomechanical Photonic Crystal Cavity","authors":"F. Galeotti, I. S. Vollenbroek, M. Petruzzella, F. Pagliano, F. V. van Otten, Ž. Zobenica, H. S. Marnani, A. Mohtashami, R. W. van der Heijden, A. Fiore","doi":"10.1109/CLEOE-EQEC.2019.8871530","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8871530","url":null,"abstract":"A nano-opto-electro-mechanical transducer for displacement sensing is presented. It consists of a double-membrane photonic crystal cavity integrated with electro-optical read-out and on-chip light-delivery. The operation is demonstrated by atomic force microscope actuation and photocurrent sensing.","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"36 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77825059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-17DOI: 10.1109/CLEOE-EQEC.2019.8872781
V. Mylnikov, E. Rafailov, G. Sokolovskii
Conical refraction (CR) is observed for the light propagating along the optical axis of a biaxial crystal. In this case a narrow beam evolves as a hollow double-walled cylinder of light behind the exit facet of a crystal. Despite of almost two-centuries-long research, CR was slow with practical applications, mainly due to the difficulties associated with cutting of the biaxial crystals with the necessary precision. However, a number of recent papers report on the emerging applications of CR for the realisation of ultra-efficient CR lasers, lasers with CR output, optical trapping with CR beams, utilisation of CR for quantum-computing, cryptography and super-resolution microscopy (see e.g. [1] and references therein). However, one of the most novel and intriguing phenomena within the CR are associated with utilization of vortex input beams. These are capable to completely change the familiar CR patterns [2] and trigger many new applications. In this sense, studies of CR with Laguerre-Gaussian beams LGl0, which are the simplest vortices, may be very fruitful (here, I is the index determining vortex charge): These already have demonstrated specific new properties of CR, such as formation of a multi-ring image in the Lloyd plane [2].
{"title":"Conical Refraction with Laguerre-Gaussian Beams: From Raman Spot to ‘Anti-Raman’ Doughnut Distribution","authors":"V. Mylnikov, E. Rafailov, G. Sokolovskii","doi":"10.1109/CLEOE-EQEC.2019.8872781","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8872781","url":null,"abstract":"Conical refraction (CR) is observed for the light propagating along the optical axis of a biaxial crystal. In this case a narrow beam evolves as a hollow double-walled cylinder of light behind the exit facet of a crystal. Despite of almost two-centuries-long research, CR was slow with practical applications, mainly due to the difficulties associated with cutting of the biaxial crystals with the necessary precision. However, a number of recent papers report on the emerging applications of CR for the realisation of ultra-efficient CR lasers, lasers with CR output, optical trapping with CR beams, utilisation of CR for quantum-computing, cryptography and super-resolution microscopy (see e.g. [1] and references therein). However, one of the most novel and intriguing phenomena within the CR are associated with utilization of vortex input beams. These are capable to completely change the familiar CR patterns [2] and trigger many new applications. In this sense, studies of CR with Laguerre-Gaussian beams LGl0, which are the simplest vortices, may be very fruitful (here, I is the index determining vortex charge): These already have demonstrated specific new properties of CR, such as formation of a multi-ring image in the Lloyd plane [2].","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"1 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75501093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-17DOI: 10.1109/cleoe-eqec.2019.8871859
A. Forrest, M. Krakowski, P. Bardella, M. Cataluna
Combining the output of two or more separate, distinct superluminescent diodes (SLDs) via spectral multiplexing has the potential to produce very wide optical spectra which could prove beneficial in imaging applications1. Likewise, the implementation of a multi-section contact layout also allows for optimization of the spectral bandwidth and output power through the independent tuning of the current density in each section2. Here, we present the first comparative investigation of the output from both facets of a tapered multi-section SLD. A significant spectral asymmetry between the output of both facets was observed and was found to be widely tunable through the variation of the biasing conditions in both sections of the device. These results highlight an as yet untapped extra degree of freedom in multi-section superluminescent diodes which could be exploited to engineer the spectral bandwidth of such devices through the multiplexing of both outputs of a single device.
{"title":"Tapered Multi-Section Superluminescent Diode with Tunable Spectral Asymmetry between Narrow and Wide Facet Outputs","authors":"A. Forrest, M. Krakowski, P. Bardella, M. Cataluna","doi":"10.1109/cleoe-eqec.2019.8871859","DOIUrl":"https://doi.org/10.1109/cleoe-eqec.2019.8871859","url":null,"abstract":"Combining the output of two or more separate, distinct superluminescent diodes (SLDs) via spectral multiplexing has the potential to produce very wide optical spectra which could prove beneficial in imaging applications1. Likewise, the implementation of a multi-section contact layout also allows for optimization of the spectral bandwidth and output power through the independent tuning of the current density in each section2. Here, we present the first comparative investigation of the output from both facets of a tapered multi-section SLD. A significant spectral asymmetry between the output of both facets was observed and was found to be widely tunable through the variation of the biasing conditions in both sections of the device. These results highlight an as yet untapped extra degree of freedom in multi-section superluminescent diodes which could be exploited to engineer the spectral bandwidth of such devices through the multiplexing of both outputs of a single device.","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"14 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73182019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-17DOI: 10.1109/CLEOE-EQEC.2019.8871711
G. Rademacher, B. Puttnam, R. Luís, A. Ross-Adams, S. Gross, M. Withford, N. Riesen, Y. Sasaki, H. Furukawa, K. Saitoh, K. Aikawa, Y. Awaji, N. Wada
Space-division multiplexing (SDM) in few-mode multi-core fibers (FM-MCF) allows the transmission of multi-petabit/s data-rates over a single optical fiber. Recently, transmission of more than 1.2 Pbit/s was demonstrated in a FM-MCF with a cladding diameter of 160 μm, compatible with the standard coating diameter of 250 μm [1]. When increasing the core density in FM-MCF or the transmission distance, inter-core crosstalk can limit the achievable data rates. Inter-core crosstalk is strongly wavelength-dependent and higher-order modes in FM-MCF are expected to show a larger crosstalk penalty compared to the fundamental mode, as their mode fields extend farther into the cladding [2]. In this paper, we present an experimental investigation of the crosstalk-induced Q-factor degradation of 16-Quadrature amplitude modulation (16-QAM) signals, transmitted over a four-core three-mode fiber.
{"title":"Mode-Dependent Crosstalk Penalty in Few-Mode Multi-Core Fiber Transmission","authors":"G. Rademacher, B. Puttnam, R. Luís, A. Ross-Adams, S. Gross, M. Withford, N. Riesen, Y. Sasaki, H. Furukawa, K. Saitoh, K. Aikawa, Y. Awaji, N. Wada","doi":"10.1109/CLEOE-EQEC.2019.8871711","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8871711","url":null,"abstract":"Space-division multiplexing (SDM) in few-mode multi-core fibers (FM-MCF) allows the transmission of multi-petabit/s data-rates over a single optical fiber. Recently, transmission of more than 1.2 Pbit/s was demonstrated in a FM-MCF with a cladding diameter of 160 μm, compatible with the standard coating diameter of 250 μm [1]. When increasing the core density in FM-MCF or the transmission distance, inter-core crosstalk can limit the achievable data rates. Inter-core crosstalk is strongly wavelength-dependent and higher-order modes in FM-MCF are expected to show a larger crosstalk penalty compared to the fundamental mode, as their mode fields extend farther into the cladding [2]. In this paper, we present an experimental investigation of the crosstalk-induced Q-factor degradation of 16-Quadrature amplitude modulation (16-QAM) signals, transmitted over a four-core three-mode fiber.","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"83 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81533833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-17DOI: 10.1109/CLEOE-EQEC.2019.8873153
C. Brahms, T. Grigorova, F. Belli, J. Travers
Soliton dynamics underlie a wide range of phenomena in nonlinear fibre optics. In particular, higher-order solitons in gas-filled hollow-core photonic crystal fibre (HC-PCF) have been applied to self-compression of ultrafast laser pulses [1] and the generation of widely tuneable resonant dispersive waves (RDW) from the vacuum ultraviolet (VUV) to the visible spectral range [2]. We recently demonstrated that by moving to long, large-core hollow capillary fibres (HCF) and shorter driving pulses, these effects can be scaled by up to three orders of magnitude in pulse energy, providing unprecedented peak power in ultrafast VUV pulses as well as a route towards terawatt-scale optical attosecond pulses [3]. Here we show that by further decreasing the initial pulse duration, high-energy soliton dynamics can be obtained in HCF as short as 35 cm.
{"title":"Soliton Self-Compression and UV Dispersive Wave Emission in Compact Hollow Capillary Systems","authors":"C. Brahms, T. Grigorova, F. Belli, J. Travers","doi":"10.1109/CLEOE-EQEC.2019.8873153","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8873153","url":null,"abstract":"Soliton dynamics underlie a wide range of phenomena in nonlinear fibre optics. In particular, higher-order solitons in gas-filled hollow-core photonic crystal fibre (HC-PCF) have been applied to self-compression of ultrafast laser pulses [1] and the generation of widely tuneable resonant dispersive waves (RDW) from the vacuum ultraviolet (VUV) to the visible spectral range [2]. We recently demonstrated that by moving to long, large-core hollow capillary fibres (HCF) and shorter driving pulses, these effects can be scaled by up to three orders of magnitude in pulse energy, providing unprecedented peak power in ultrafast VUV pulses as well as a route towards terawatt-scale optical attosecond pulses [3]. Here we show that by further decreasing the initial pulse duration, high-energy soliton dynamics can be obtained in HCF as short as 35 cm.","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"5 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80146468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-17DOI: 10.1109/CLEOE-EQEC.2019.8872384
Norbert Ackerl, K. Wegener
A tenfold increase in the mean ablation depth of burst mode ablation with 1030 nm, 1 ps and 25 ns time spacing is reported. The threshold fluence decreases and this finding is supported by a multi-pulse ablation study.
{"title":"Efficiency Study on Single Pulse, Burst Mode and Multi Pulse Ultra-Short Pulsed Ablation of Pure Copper","authors":"Norbert Ackerl, K. Wegener","doi":"10.1109/CLEOE-EQEC.2019.8872384","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8872384","url":null,"abstract":"A tenfold increase in the mean ablation depth of burst mode ablation with 1030 nm, 1 ps and 25 ns time spacing is reported. The threshold fluence decreases and this finding is supported by a multi-pulse ablation study.","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"84 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77857491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-17DOI: 10.1109/CLEOE-EQEC.2019.8873357
D. Dumas, J. Kirdoda, P. Vines, K. Kuzmenko, R. Millar, G. Buller, D. Paul
Ge on Si SPAD devices hold promise for cost effective use in vehicular LIDAR [1], quantum optics, quantum communications, and other applications. Previous Ge on SI SPAD devices using mesa structures have shown high dark count rate (DCR) and low single photon detection efficiency (SPDE) [2]. The novel planar device design demonstrated here shows low DCR and high SPDE at short-wave infrared wavelengths. The novel design allows better performance by confining the high field regions using an implanted charge sheet and small top contact region. This design removes the interaction between etched sidewalls and high electric fields seen in mesa devices. We have fabricated devices with a 100 μm diameter charge sheet and a 90 μ m diameter top contact. TCSPC measurements were taken at 78 K, 100 K, 125 K, using 1310 nm light with << 1 photon per pulse on average and 50 ns gate times (Fig. 1). A record high SPDE of 38% for Ge-on-Si SPADs was measured for a device temperature of 125 K with an excess bias of 5.5 %, and a record low NEP of 2× 10−16WHz−1/2 was demonstrated at 78 K.
锗硅SPAD器件有望在车载激光雷达[1]、量子光学、量子通信和其他应用中具有成本效益。以往使用平台结构的Ge on SI SPAD器件显示出高暗计数率(DCR)和低单光子探测效率(SPDE)[2]。本文所展示的新型平面器件在短波红外波段具有低DCR和高SPDE。这种新颖的设计通过使用植入的电荷片和小的顶部接触区域来限制高场区域，从而获得更好的性能。这种设计消除了蚀刻侧壁和高电场之间的相互作用。我们已经制作了直径为100 μm的电荷片和直径为90 μm的顶部接触的器件。TCSPC测量分别在78 K, 100 K, 125 K下进行，使用1310 nm光，平均每脉冲<< 1光子，50 ns栅极时间(图1)。在125 K的器件温度下，测量到Ge-on-Si spad的最高SPDE为38%，过量偏置为5.5%，在78 K下显示出创纪录的低NEP为2× 10−16WHz−1/2。
{"title":"Ge-On-Si High Efficiency Spads at 1310 Nm","authors":"D. Dumas, J. Kirdoda, P. Vines, K. Kuzmenko, R. Millar, G. Buller, D. Paul","doi":"10.1109/CLEOE-EQEC.2019.8873357","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8873357","url":null,"abstract":"Ge on Si SPAD devices hold promise for cost effective use in vehicular LIDAR [1], quantum optics, quantum communications, and other applications. Previous Ge on SI SPAD devices using mesa structures have shown high dark count rate (DCR) and low single photon detection efficiency (SPDE) [2]. The novel planar device design demonstrated here shows low DCR and high SPDE at short-wave infrared wavelengths. The novel design allows better performance by confining the high field regions using an implanted charge sheet and small top contact region. This design removes the interaction between etched sidewalls and high electric fields seen in mesa devices. We have fabricated devices with a 100 μm diameter charge sheet and a 90 μ m diameter top contact. TCSPC measurements were taken at 78 K, 100 K, 125 K, using 1310 nm light with << 1 photon per pulse on average and 50 ns gate times (Fig. 1). A record high SPDE of 38% for Ge-on-Si SPADs was measured for a device temperature of 125 K with an excess bias of 5.5 %, and a record low NEP of 2× 10−16WHz−1/2 was demonstrated at 78 K.","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"109 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80697209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-17DOI: 10.1109/CLEOE-EQEC.2019.8871538
N. Bigler, J. Pupeikis, S. Hrisafov, L. Gallmann, C. Phillips, U. Keller
Mid-infrared (mid-IR) laser sources with a high repetition rate and peak power are particularly interesting for strong-field and attosecond science, enabling fast measurements and shorter attosecond pulses via the high-harmonic cut-off [1]. Here we demonstrate our optical parametric chirped pulse amplification (OPCPA) system delivering pulses with 12.6 W average power and a pulse duration of 14.4 fs at 100 kHz with a center wavelength of 2.5 μm. This corresponds to a record-high mid-IR (above 2 μώ) peak power of 6.3 GW at 100 kHz repetition rate [2]. Moreover we present a new time-gated pulse shaping scheme which enables optimal compression of the high-power mid-IR pulses [3].
{"title":"High-Power and Sub-Two-Cycle 2.5 μm Optical Parametric Chirped Pulse Amplification System","authors":"N. Bigler, J. Pupeikis, S. Hrisafov, L. Gallmann, C. Phillips, U. Keller","doi":"10.1109/CLEOE-EQEC.2019.8871538","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8871538","url":null,"abstract":"Mid-infrared (mid-IR) laser sources with a high repetition rate and peak power are particularly interesting for strong-field and attosecond science, enabling fast measurements and shorter attosecond pulses via the high-harmonic cut-off [1]. Here we demonstrate our optical parametric chirped pulse amplification (OPCPA) system delivering pulses with 12.6 W average power and a pulse duration of 14.4 fs at 100 kHz with a center wavelength of 2.5 μm. This corresponds to a record-high mid-IR (above 2 μώ) peak power of 6.3 GW at 100 kHz repetition rate [2]. Moreover we present a new time-gated pulse shaping scheme which enables optimal compression of the high-power mid-IR pulses [3].","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"1 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82173060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-17DOI: 10.1109/CLEOE-EQEC.2019.8873292
K. Tokmakov, M. Sumetsky
There is a growing interest to the multi-disciplinary field of droplet microfluidics having applications in physics, chemistry, biology, surface science, colloidal liquid dynamics etc. [1, 2]. Usually, optical sensing methods characterize the droplets with the spatial resolution determined by the wavelength of light, i.e., comparable with 1 micron. Alternatively, the approach suggested in Ref. [3] allows to determine the refractive index variation of submicron-thick liquid layers adjacent to the surface of microcapillaries. Microfluidic sensing in Ref. [3] was performed by measurement of the resonant whispering gallery mode (WGM) spectrum. Specifically, WGMs were launched into the microcapillary using the normally attached micron-diameter waist of a biconical fibre taper connected to the light source and optical spectrum analyser (OSA) as illustrated in Fig. 1(a). Evanescent coupling of WGMs to the interior of the microcapillary allowed to detect the refractive index variation of liquid by monitoring the shifts of the WGM resonances.
{"title":"Monitoring the Evaporation Dynamics of a Water Droplet Inside a Microcapillary with Nanometre-Scale Precision","authors":"K. Tokmakov, M. Sumetsky","doi":"10.1109/CLEOE-EQEC.2019.8873292","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8873292","url":null,"abstract":"There is a growing interest to the multi-disciplinary field of droplet microfluidics having applications in physics, chemistry, biology, surface science, colloidal liquid dynamics etc. [1, 2]. Usually, optical sensing methods characterize the droplets with the spatial resolution determined by the wavelength of light, i.e., comparable with 1 micron. Alternatively, the approach suggested in Ref. [3] allows to determine the refractive index variation of submicron-thick liquid layers adjacent to the surface of microcapillaries. Microfluidic sensing in Ref. [3] was performed by measurement of the resonant whispering gallery mode (WGM) spectrum. Specifically, WGMs were launched into the microcapillary using the normally attached micron-diameter waist of a biconical fibre taper connected to the light source and optical spectrum analyser (OSA) as illustrated in Fig. 1(a). Evanescent coupling of WGMs to the interior of the microcapillary allowed to detect the refractive index variation of liquid by monitoring the shifts of the WGM resonances.","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"9 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81657160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-17DOI: 10.1109/cleoe-eqec.2019.8871454
Hao Zhang, A. Antoncecchi, S. Edward, P. Planken, S. Witte
Ultrafast laser pulses incident on metals can lead to the generation of coherent phonon wave packets with frequencies in the gigahertz to terahertz range [1,2]. Material characterization using such ultrafast laser-induced ultrasound pulses provides access to a frequency range that is inaccessible by any other means. Our objective is to study the optical and acoustic properties of materials by generating and detecting ultrasound waves with ultrafast laser pulses. To generate high frequency acoustic waves in a way that also optimizes their detection, we use a pair of crossed 40 fs femtosecond pump pulses at 400 nm wavelength to project interference fringes on the surface of thin metal films. Because ultrasound is only generated in the interference maxima, this approach produces a spatially periodic array of acoustic pulses. The acoustic pulses propagate through the film and are reflected at the back surface. A delayed probe pulse (30 fs, 800 nm) then detects the returning acoustic echo by detecting a change in the optical response that occurs every time an acoustic echo returns to the surface. Because a periodic array of ultrasound waves was produced, we can detect the first order diffraction of the probe beam by this ‘acoustic grating’. By performing these measurements in thin free-standing metal membranes, the influence of substrate interfaces is eliminated, and acoustic attenuation is only caused by propagation in the metal, providing clean measurements of the metal parameters without external factors.
{"title":"Characterization of Thin Metal Films by Ultrafast Laser Induced Ultrasound","authors":"Hao Zhang, A. Antoncecchi, S. Edward, P. Planken, S. Witte","doi":"10.1109/cleoe-eqec.2019.8871454","DOIUrl":"https://doi.org/10.1109/cleoe-eqec.2019.8871454","url":null,"abstract":"Ultrafast laser pulses incident on metals can lead to the generation of coherent phonon wave packets with frequencies in the gigahertz to terahertz range [1,2]. Material characterization using such ultrafast laser-induced ultrasound pulses provides access to a frequency range that is inaccessible by any other means. Our objective is to study the optical and acoustic properties of materials by generating and detecting ultrasound waves with ultrafast laser pulses. To generate high frequency acoustic waves in a way that also optimizes their detection, we use a pair of crossed 40 fs femtosecond pump pulses at 400 nm wavelength to project interference fringes on the surface of thin metal films. Because ultrasound is only generated in the interference maxima, this approach produces a spatially periodic array of acoustic pulses. The acoustic pulses propagate through the film and are reflected at the back surface. A delayed probe pulse (30 fs, 800 nm) then detects the returning acoustic echo by detecting a change in the optical response that occurs every time an acoustic echo returns to the surface. Because a periodic array of ultrasound waves was produced, we can detect the first order diffraction of the probe beam by this ‘acoustic grating’. By performing these measurements in thin free-standing metal membranes, the influence of substrate interfaces is eliminated, and acoustic attenuation is only caused by propagation in the metal, providing clean measurements of the metal parameters without external factors.","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"9 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78311570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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