Pub Date : 2019-06-23DOI: 10.1109/CLEOE-EQEC.2019.8872372
Mircea Catuneanu, R. Hamerly, Nirav Annavarapu, Shahryar Sabouri, K. Jamshidi
To overcome the interconnect problem of CMOS Neural Network (NN) implementations (increased power consumption while inhibiting speed), small-scale linear optics-based solutions have been proposed to replace the electronic NN layer in multiple works — e.g. [1–3]. Nevertheless, an all-optical NN is difficult to achieve as it would imply substituting the existing electro-optic signal conversion and digital-driven activation function necessary between NN layers. In this work, we demonstrate how feedback controlled microring resonators (MRR) can be used as activation functions in NNs. The design we focus on is shown in Fig. 1-a. Pulses of light at different frequencies carry signals while weights are applied using PIN ring modulators with proper free spectral range. Pulses are used to ensure that the detuning due to heating of the device is mostly avoided. The light is then coupled in the main ring resonator responsible for the non-linear transfer function. The power dependent response is governed by an interplay between free carrier dispersion and free carrier absorption [4]. An electronic feedback loop will ensure carrier lifetime control, crucial for output stability and reproducibility. The output of this resonator is then filtered again to extract the necessary signal, before passing it to the next NN layer.
{"title":"Nonlinear Activation Function Generation Based on Silicon Microring Resonators for Integrated Photonic Neural Networks","authors":"Mircea Catuneanu, R. Hamerly, Nirav Annavarapu, Shahryar Sabouri, K. Jamshidi","doi":"10.1109/CLEOE-EQEC.2019.8872372","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8872372","url":null,"abstract":"To overcome the interconnect problem of CMOS Neural Network (NN) implementations (increased power consumption while inhibiting speed), small-scale linear optics-based solutions have been proposed to replace the electronic NN layer in multiple works — e.g. [1–3]. Nevertheless, an all-optical NN is difficult to achieve as it would imply substituting the existing electro-optic signal conversion and digital-driven activation function necessary between NN layers. In this work, we demonstrate how feedback controlled microring resonators (MRR) can be used as activation functions in NNs. The design we focus on is shown in Fig. 1-a. Pulses of light at different frequencies carry signals while weights are applied using PIN ring modulators with proper free spectral range. Pulses are used to ensure that the detuning due to heating of the device is mostly avoided. The light is then coupled in the main ring resonator responsible for the non-linear transfer function. The power dependent response is governed by an interplay between free carrier dispersion and free carrier absorption [4]. An electronic feedback loop will ensure carrier lifetime control, crucial for output stability and reproducibility. The output of this resonator is then filtered again to extract the necessary signal, before passing it to the next NN layer.","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"66 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81478258","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 : 2019-06-23DOI: 10.1109/CLEOE-EQEC.2019.8873411
A. Popp, V. Bock, F. Sedlmeir, C. Müller, N. Haarlammert, T. Schreiber, C. Marquardt, A. Tünnermann, G. Leuchs
Ytterbium-doped fiber laser amplifiers are known for their high single-pass gain and average powers up to the kilowatt range, while maintaining single-mode output. An upper limitation for the achievable output power is given by transverse mode instabilities (TMI). Due to the interference with higher order modes that create a thermally induced long period grating, chaotic power transfer happens above a certain threshold, which degrades the beam quality. It has been shown that this effect can be influenced by manipulating the grating strength itself. It has also been shown that a certain phase relation of the grating to the guided modes is necessary to efficiently transfer power or hinder the effect by phase disturbance [1]. A natural phase disturbance is given by noise, which is introduced by the pump or seed source in a fiber amplifer. In this contribution, we experimentally investigate the amount of intensity noise in a fiber-pre-amplifer, which is typically used in kW experiments and relate it to the fundamental shot noise limit (SNL). In the experiments, we used a single-frequency external cavity diode laser as a low noise source and amplify it by 30 dB from 10 mW to an output power of 10 W. This is a typical pre-amplifier configuration, before such sources can be amplified to the kW level. The fiber amplifier is a double-clad fiber with a 10/125 μm geometry, pumped by a wavelength stabilized pump diode at 976 nm via a monolithic pump coupler. In order to prevent stimulated Brillouin scattering, the seed laser is phase modulated by a combination of a sinusoid and white noise and thus broadened to 50 GHz linewidth. The noise measurements are done by balanced self-homodyne detection including optimized photodiode readout circuits spanning different frequency ranges. The recorded spectra are given in Fig. 1. The SNL was verified through an attenuation measurement for the subtracted detector signals. Finally, the measured excess noise values are fitted by their corresponding second-order polynomial power dependency and extrapolated to the full power of the amplifier. The seed source, phase modulator and fiber amplifier have been characterized in this setup separately to investigate their contributions. For the fiber amplifier, both co- and counter-pumping configuration, are analysed. Due to detector limitations, all given spectra are measured at an optical power in the mW regime corresponding to approx. 30 dB of attenuation in the amplifiers.
{"title":"Investigation of Noise Sources Down to the Shot-Noise Limit in Yb-Doped Fiber Amplifers for TMI Investigations","authors":"A. Popp, V. Bock, F. Sedlmeir, C. Müller, N. Haarlammert, T. Schreiber, C. Marquardt, A. Tünnermann, G. Leuchs","doi":"10.1109/CLEOE-EQEC.2019.8873411","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8873411","url":null,"abstract":"Ytterbium-doped fiber laser amplifiers are known for their high single-pass gain and average powers up to the kilowatt range, while maintaining single-mode output. An upper limitation for the achievable output power is given by transverse mode instabilities (TMI). Due to the interference with higher order modes that create a thermally induced long period grating, chaotic power transfer happens above a certain threshold, which degrades the beam quality. It has been shown that this effect can be influenced by manipulating the grating strength itself. It has also been shown that a certain phase relation of the grating to the guided modes is necessary to efficiently transfer power or hinder the effect by phase disturbance [1]. A natural phase disturbance is given by noise, which is introduced by the pump or seed source in a fiber amplifer. In this contribution, we experimentally investigate the amount of intensity noise in a fiber-pre-amplifer, which is typically used in kW experiments and relate it to the fundamental shot noise limit (SNL). In the experiments, we used a single-frequency external cavity diode laser as a low noise source and amplify it by 30 dB from 10 mW to an output power of 10 W. This is a typical pre-amplifier configuration, before such sources can be amplified to the kW level. The fiber amplifier is a double-clad fiber with a 10/125 μm geometry, pumped by a wavelength stabilized pump diode at 976 nm via a monolithic pump coupler. In order to prevent stimulated Brillouin scattering, the seed laser is phase modulated by a combination of a sinusoid and white noise and thus broadened to 50 GHz linewidth. The noise measurements are done by balanced self-homodyne detection including optimized photodiode readout circuits spanning different frequency ranges. The recorded spectra are given in Fig. 1. The SNL was verified through an attenuation measurement for the subtracted detector signals. Finally, the measured excess noise values are fitted by their corresponding second-order polynomial power dependency and extrapolated to the full power of the amplifier. The seed source, phase modulator and fiber amplifier have been characterized in this setup separately to investigate their contributions. For the fiber amplifier, both co- and counter-pumping configuration, are analysed. Due to detector limitations, all given spectra are measured at an optical power in the mW regime corresponding to approx. 30 dB of attenuation in the amplifiers.","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"26 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81871070","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 : 2019-06-23DOI: 10.1109/CLEOE-EQEC.2019.8873414
S. Nanz, A. Abass, E. Slivina, P. Piechulla, A. Sprafke, R. Wehrspohn, C. Rockstuhl
Light management in photovoltaics continues to be an important ingredient when working towards high efficiency devices. Various approaches have been perceived. Besides spectral modification, e.g. based on up- or down-conversion, the spatial and angular redistribution of light is important. For the latter aspect, on which we concentrate here, various supporting photonic structures were suggested, e.g. photonic crystals, metallic nanostructures, or textured interfaces. From a higher executive perspective we can categorize most structures as being either periodic or random. The emergence of such material classes is explained by the fabrication means. The Fourier spectrum, i.e. the angular distribution with which photonic modes can be excited from such structures beyond specific near-field effects is either discrete and wavelength sensitive or unspecific and spectrally flat. Both combinations are far from optimum when integrating them into photovoltaic devices.
{"title":"Tailored Disorder for the Light Management in Photovoltaics","authors":"S. Nanz, A. Abass, E. Slivina, P. Piechulla, A. Sprafke, R. Wehrspohn, C. Rockstuhl","doi":"10.1109/CLEOE-EQEC.2019.8873414","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8873414","url":null,"abstract":"Light management in photovoltaics continues to be an important ingredient when working towards high efficiency devices. Various approaches have been perceived. Besides spectral modification, e.g. based on up- or down-conversion, the spatial and angular redistribution of light is important. For the latter aspect, on which we concentrate here, various supporting photonic structures were suggested, e.g. photonic crystals, metallic nanostructures, or textured interfaces. From a higher executive perspective we can categorize most structures as being either periodic or random. The emergence of such material classes is explained by the fabrication means. The Fourier spectrum, i.e. the angular distribution with which photonic modes can be excited from such structures beyond specific near-field effects is either discrete and wavelength sensitive or unspecific and spectrally flat. Both combinations are far from optimum when integrating them into photovoltaic devices.","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"115 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78650659","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 : 2019-06-23DOI: 10.1109/CLEOE-EQEC.2019.8872541
J. Popp
In recent years, Raman spectroscopic approaches have established themselves as powerful analytical diagnostic methods to research a wide range of biomedical problems [1]. In this contribution, we review our latest results on researching Raman spectroscopic methods for the diagnosis and targeted therapy of infectious diseases and cancer. These investigations are accompanied by the development of spectroscopic instrumentations, which can be used outside specialized optics labs in a clinical environment.
{"title":"The Potential of Linear and Non-Linear Raman Spectroscopy for Bedside and Intraoperative Medical Diagnosis and Therapy","authors":"J. Popp","doi":"10.1109/CLEOE-EQEC.2019.8872541","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8872541","url":null,"abstract":"In recent years, Raman spectroscopic approaches have established themselves as powerful analytical diagnostic methods to research a wide range of biomedical problems [1]. In this contribution, we review our latest results on researching Raman spectroscopic methods for the diagnosis and targeted therapy of infectious diseases and cancer. These investigations are accompanied by the development of spectroscopic instrumentations, which can be used outside specialized optics labs in a clinical environment.","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"12 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78884557","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 : 2019-06-23DOI: 10.1109/CLEOE-EQEC.2019.8872385
F. Eltes, J. Ortmann, P. Castera, D. Urbonas, D. Caimi, L. Czornomaz, P. Sanchis, J. Fompeyrine, S. Abel
Integrated photonics is a key technology platform for optical communication, sensing, and data processing. Driven by the success of the CMOS industry and the resulting maturity of silicon-based fabrication methods, silicon photonics has evolved as an important candidate to realize integrated photonic circuits (PICs) in a cost-efficient and scalable way. Electrical control of the optical properties is critical in PICs: Fast electro-optical modulators are essential to reach high data rates, low-loss switches are needed to dynamically reconfigure networks, and low-power tuning elements are important to compensate temperature fluctuations. Traditionally, such components are implemented in silicon photonics by exploiting the plasma-dispersion effect [1] or Joule heating [2], which are, however, intrinsically linked with optical absorption or high power consumption. These challenges could be solved by using the Pockels effect as an electro-optic switching mechanism. However, because silicon lacks a Pockels effect, other materials with a non-vanishing Pockels effect need to be integrated on the technology platform.
{"title":"Silicon-Integrated High-Speed Modulators Based on Barium Titanate with Record-Large Pockels Coefficients","authors":"F. Eltes, J. Ortmann, P. Castera, D. Urbonas, D. Caimi, L. Czornomaz, P. Sanchis, J. Fompeyrine, S. Abel","doi":"10.1109/CLEOE-EQEC.2019.8872385","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8872385","url":null,"abstract":"Integrated photonics is a key technology platform for optical communication, sensing, and data processing. Driven by the success of the CMOS industry and the resulting maturity of silicon-based fabrication methods, silicon photonics has evolved as an important candidate to realize integrated photonic circuits (PICs) in a cost-efficient and scalable way. Electrical control of the optical properties is critical in PICs: Fast electro-optical modulators are essential to reach high data rates, low-loss switches are needed to dynamically reconfigure networks, and low-power tuning elements are important to compensate temperature fluctuations. Traditionally, such components are implemented in silicon photonics by exploiting the plasma-dispersion effect [1] or Joule heating [2], which are, however, intrinsically linked with optical absorption or high power consumption. These challenges could be solved by using the Pockels effect as an electro-optic switching mechanism. However, because silicon lacks a Pockels effect, other materials with a non-vanishing Pockels effect need to be integrated on the technology platform.","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"8 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75964804","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 : 2019-06-23DOI: 10.1109/CLEOE-EQEC.2019.8871925
Yuk Shan Cheng, D. Xiao, R. McCracken, D. Reid
The Extremely Large Telescope (ELT), currently under construction in Chile, aims to investigate exoplanet atmospheric spectroscopy, star / planet formation and evolution, and cosmology and fundamental physics with a broadband high-resolution spectrograph, designated ELT-HIRES. Comprising four modules covering wavelengths from 370–2500 nm, this instrument requires laser comb calibration with mode spacings from 32 GHz (<600 nm) to 6 GHz (>1950 nm). As illustrated by our recent review paper [1], approaches to date based on nonlinear broadening of a single ultrafast oscillator still fall significantly short of the required coverage. Here we present a new approach yielding a nearly-continuous 500–2200 nm 1-GHz comb from dual supercontinua sources pumped by an 805-nm Ti:sapphire oscillator and phase coherent 1610-nm pulses from a degenerate optical parametric oscillator (OPO) [2].
{"title":"Towards a Visible to Mid-Infrared Astrocomb for the Extremely Large Telescope","authors":"Yuk Shan Cheng, D. Xiao, R. McCracken, D. Reid","doi":"10.1109/CLEOE-EQEC.2019.8871925","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8871925","url":null,"abstract":"The Extremely Large Telescope (ELT), currently under construction in Chile, aims to investigate exoplanet atmospheric spectroscopy, star / planet formation and evolution, and cosmology and fundamental physics with a broadband high-resolution spectrograph, designated ELT-HIRES. Comprising four modules covering wavelengths from 370–2500 nm, this instrument requires laser comb calibration with mode spacings from 32 GHz (<600 nm) to 6 GHz (>1950 nm). As illustrated by our recent review paper [1], approaches to date based on nonlinear broadening of a single ultrafast oscillator still fall significantly short of the required coverage. Here we present a new approach yielding a nearly-continuous 500–2200 nm 1-GHz comb from dual supercontinua sources pumped by an 805-nm Ti:sapphire oscillator and phase coherent 1610-nm pulses from a degenerate optical parametric oscillator (OPO) [2].","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"15 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88274929","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 : 2019-06-23DOI: 10.1109/CLEOE-EQEC.2019.8872257
M. Lezius, B. Probster, O. Mandel, M. Giunta, R. Holzwarth
Since its invention in the late 1990s, the frequency comb technology revolutionized the world of optical frequency metrology [1] and is now widely available as of-the-shelf product around the globe. While promising use cases for space-based applications exist, the space technology readiness, particularly regarding miniaturization and ruggedness, remains an obstacle for its deployment. In April 2015 and January 2016 the first frequency comb system FOKUS I was launched into space on a TEXUS sounding rocket, demonstrating the robustness and reliability of the technology [2].
{"title":"FOKUS II — Space Flight of a Vacuum Compatible Dual Frequency Comb System","authors":"M. Lezius, B. Probster, O. Mandel, M. Giunta, R. Holzwarth","doi":"10.1109/CLEOE-EQEC.2019.8872257","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8872257","url":null,"abstract":"Since its invention in the late 1990s, the frequency comb technology revolutionized the world of optical frequency metrology [1] and is now widely available as of-the-shelf product around the globe. While promising use cases for space-based applications exist, the space technology readiness, particularly regarding miniaturization and ruggedness, remains an obstacle for its deployment. In April 2015 and January 2016 the first frequency comb system FOKUS I was launched into space on a TEXUS sounding rocket, demonstrating the robustness and reliability of the technology [2].","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"74 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88338035","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 : 2019-06-23DOI: 10.1109/CLEOE-EQEC.2019.8872608
P. Roy, Rei Abe-Yoshizumi, Yoshitaka Kato, H. Kandori, T. Buckup
The light induced isomerization of retinal protonated Schiff base (RPSB) inside the protein pocket is one of the fastest (
视网膜蛋白袋内质子化席夫碱(RPSB)的光诱导异构化是自然界中最快(
{"title":"Isomerization Dynamics of Wild Type and Mutated Anabaena Sensory Rhodopsin Mapped by Time-Resolved Coherent Raman Spectroscopy","authors":"P. Roy, Rei Abe-Yoshizumi, Yoshitaka Kato, H. Kandori, T. Buckup","doi":"10.1109/CLEOE-EQEC.2019.8872608","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8872608","url":null,"abstract":"The light induced isomerization of retinal protonated Schiff base (RPSB) inside the protein pocket is one of the fastest (<ps) and most stereo-selective photochemical reactions in nature [1]. The ground state structure of the RPSB and its surrounding protein architecture are known to play a central role in this reaction. It has been a longstanding question how each factor individually influences the reaction dynamics. In this context, Anabaena Sensory Rhodopsin (ASR), a recently discovered microbial retinal protein, serves as an ideal system to answer this question as it binds two structural isomers (all-trans and 13-cis) of the RPSB within the same protein constructions in its photocycle. In this work, the photo-isomerization dynamics of the RPSB in ASR has been explored with the help of time resolved coherent Raman techniques like pump-degenerate four-wave-mixing (pump-DFWM) (Fig. 1(a)) and pump-impulsive vibrational spectroscopy (pump-IVS). Both methods report on the structural changes of the RPSB during the photochemical reaction by tracking the transient frequency shifts of the vibrational modes in the excited state.","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"57 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88423558","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 : 2019-06-23DOI: 10.1109/CLEOE-EQEC.2019.8872454
Goronwy Tawy, M. Damzen
Red-diode-pumped Alexandrite lasers has proven to be an efficient method of generating light in the near infrared with broad tunability from 714 to 818 nm recently demonstrated [1]. Conventionally, tunable Alexandrite lasers have used wavelength selective elements such as birefringent filters or external gratings [1, 2]. In this work wavelength tuning is obtained by exploiting the birefringence of the crystal to use the crystal itself as the wavelength selective element, greatly simplifying the cavity and reducing innecessary loss components.
{"title":"Tunable and Dual Wavelength Alexandrite Laser using the Crystal Birefringence","authors":"Goronwy Tawy, M. Damzen","doi":"10.1109/CLEOE-EQEC.2019.8872454","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8872454","url":null,"abstract":"Red-diode-pumped Alexandrite lasers has proven to be an efficient method of generating light in the near infrared with broad tunability from 714 to 818 nm recently demonstrated [1]. Conventionally, tunable Alexandrite lasers have used wavelength selective elements such as birefringent filters or external gratings [1, 2]. In this work wavelength tuning is obtained by exploiting the birefringence of the crystal to use the crystal itself as the wavelength selective element, greatly simplifying the cavity and reducing innecessary loss components.","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"22 1","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82749286","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 : 2019-06-23DOI: 10.1109/CLEOE-EQEC.2019.8872371
M. Karow, D. Martin, P. D. Casa, G. Erbert, P. Crump
High power, efficient diode-laser bars with narrow far field angles are sought for many applications, for example in the 9xx nm-range for the pumping of Yb:YAG disc and slab lasers [1,2]. In previous work, broad-area (BA) diode-laser bars with 4 mm resonator length operated with high conversion efficiency η = 62% at operating power Pop = 1 kW in quasi-continuous wave testing (200 μs, 10 Hz), by using low optical loss and low-resistivity vertical structures and high fill-factors (∼70%) [1]. Lateral far field (95% power) was Θ95% > 10° [2]. However, higher η and narrower Θ95% are needed for industrial application, and we seek improvements by altering the lateral bar structure for a fixed vertical design (from [1], wavelength λ = 930 nm, loss αi ≤ 0.4 cm−1).
{"title":"Narrower Far Field and Higher Efficiency in 1 kW Diode-Laser Bars using Improved Lateral Structuring","authors":"M. Karow, D. Martin, P. D. Casa, G. Erbert, P. Crump","doi":"10.1109/CLEOE-EQEC.2019.8872371","DOIUrl":"https://doi.org/10.1109/CLEOE-EQEC.2019.8872371","url":null,"abstract":"High power, efficient diode-laser bars with narrow far field angles are sought for many applications, for example in the 9xx nm-range for the pumping of Yb:YAG disc and slab lasers [1,2]. In previous work, broad-area (BA) diode-laser bars with 4 mm resonator length operated with high conversion efficiency η = 62% at operating power Pop = 1 kW in quasi-continuous wave testing (200 μs, 10 Hz), by using low optical loss and low-resistivity vertical structures and high fill-factors (∼70%) [1]. Lateral far field (95% power) was Θ95% > 10° [2]. However, higher η and narrower Θ95% are needed for industrial application, and we seek improvements by altering the lateral bar structure for a fixed vertical design (from [1], wavelength λ = 930 nm, loss αi ≤ 0.4 cm−1).","PeriodicalId":6714,"journal":{"name":"2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)","volume":"277 ","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2019-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91461363","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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