Pub Date : 1900-01-01DOI: 10.1364/slada.1995.tue.3
M. K. Haldar, F. Mendis, J. Wang
Subcarrier multiplexed (SCM) optical communication systems have been studied by many researchers for their attractiveness in providing simple, low-cost and broad-band optical fibre communications. In practical SCM systems, some light unintentionally fed back into the laser diode through various discontinuities such as splices adversely affect the performance of directly modulated semiconductor lasers. Many studies have been done carried out both theoretically and experimentally[1-4]. Using small signal perturbation method, Helms[2] gave expressions for modulation response, third order two carrier intermodulation distortion and second harmonic distortion which were shown to be in reasonable agreement with experimental results, especially when the modulating signals are small. Nevertheless, when modulating signals are large, small signal analysis may lose its accuracy and validity. In this paper, we use numerical methods to study the distortion produced by a directly modulated laser diode with weak coherent optical feedback.
{"title":"Numerical Analysis of Distortions in Directly Modulated Semiconductor Lasers in the Presence of Weak Optical Feedback","authors":"M. K. Haldar, F. Mendis, J. Wang","doi":"10.1364/slada.1995.tue.3","DOIUrl":"https://doi.org/10.1364/slada.1995.tue.3","url":null,"abstract":"Subcarrier multiplexed (SCM) optical communication systems have been studied by many researchers for their attractiveness in providing simple, low-cost and broad-band optical fibre communications. In practical SCM systems, some light unintentionally fed back into the laser diode through various discontinuities such as splices adversely affect the performance of directly modulated semiconductor lasers. Many studies have been done carried out both theoretically and experimentally[1-4]. Using small signal perturbation method, Helms[2] gave expressions for modulation response, third order two carrier intermodulation distortion and second harmonic distortion which were shown to be in reasonable agreement with experimental results, especially when the modulating signals are small. Nevertheless, when modulating signals are large, small signal analysis may lose its accuracy and validity. In this paper, we use numerical methods to study the distortion produced by a directly modulated laser diode with weak coherent optical feedback.","PeriodicalId":365685,"journal":{"name":"Semiconductor Lasers Advanced Devices and Applications","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128072441","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 : 1900-01-01DOI: 10.1364/slada.1995.tub.1
J. Abshire, J. Rall
Takeuchi et al. [1,2] first reported aerosol lidar measurements using an AlGaAs laser modulated with a pseudo-noise (PN) code in 1986. Recently, we have reported the design, theory and measurements [3-5] made with our breadboard PN aerosol lidar, which uses a photon counting detector and histogram-correlate receiver processor.
{"title":"Miniature Lidar using Diode Lasers Modulated with PN Codes","authors":"J. Abshire, J. Rall","doi":"10.1364/slada.1995.tub.1","DOIUrl":"https://doi.org/10.1364/slada.1995.tub.1","url":null,"abstract":"Takeuchi et al. [1,2] first reported aerosol lidar measurements using an AlGaAs laser modulated with a pseudo-noise (PN) code in 1986. Recently, we have reported the design, theory and measurements [3-5] made with our breadboard PN aerosol lidar, which uses a photon counting detector and histogram-correlate receiver processor.","PeriodicalId":365685,"journal":{"name":"Semiconductor Lasers Advanced Devices and Applications","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126958777","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 : 1900-01-01DOI: 10.1364/slada.1995.tue.4
W. Hsin
Most of the published papers on the above-threshold simulation for DFB lasers utilize the powerful transfer matrix method (TMM) to include the longitudinal variations of the carrier and photon profiles caused by spatial hole burning and gain saturation effects at high output power[1]-[7]. However the approaches used to calculate the above-threshold behaviors were not correct. The most general mistakes are: (i). The use of the wrong threshold condition for the lasing mode both at and above threshold[2]- [5],[7] (ii). The iteration algorithm used to solve the above-threshold behavior for higher order DFB modes did not include the influence of the lasing mode properly[1],[2],[4],[5],[7].
{"title":"A Correct Way to Model Arbitrary Complex Distributed FeedBack (DFB) Lasers in The Above Threshold Regime","authors":"W. Hsin","doi":"10.1364/slada.1995.tue.4","DOIUrl":"https://doi.org/10.1364/slada.1995.tue.4","url":null,"abstract":"Most of the published papers on the above-threshold simulation for DFB lasers utilize the powerful transfer matrix method (TMM) to include the longitudinal variations of the carrier and photon profiles caused by spatial hole burning and gain saturation effects at high output power[1]-[7]. However the approaches used to calculate the above-threshold behaviors were not correct. The most general mistakes are: (i). The use of the wrong threshold condition for the lasing mode both at and above threshold[2]- [5],[7] (ii). The iteration algorithm used to solve the above-threshold behavior for higher order DFB modes did not include the influence of the lasing mode properly[1],[2],[4],[5],[7].","PeriodicalId":365685,"journal":{"name":"Semiconductor Lasers Advanced Devices and Applications","volume":"24 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114093198","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 : 1900-01-01DOI: 10.1364/slada.1995.tuc.1
R. Lang, R. Parke, D. Mehuys, S. O’Brien, J. Major, J. Osinski, G. Harnagel, F. Shum, D. Welch
Coherent semiconductor sources based on flared amplifiers — monolithic and discrete MOPAs and flared unstable resonators have demonstrated the highest cw diffraction-limited output powers from semiconductor sources at wavelengths from 630 nm to beyond 2 μm. This talk will describe continuing advances in flared amplifier devices, including visible output powers approaching 1 W cw diffraction limited, powers up to 10 W diffraction-limited from monolithic devices, high-speed modulation, and more.
{"title":"High Power (>1 W) Semiconductor Lasers","authors":"R. Lang, R. Parke, D. Mehuys, S. O’Brien, J. Major, J. Osinski, G. Harnagel, F. Shum, D. Welch","doi":"10.1364/slada.1995.tuc.1","DOIUrl":"https://doi.org/10.1364/slada.1995.tuc.1","url":null,"abstract":"Coherent semiconductor sources based on flared amplifiers — monolithic and discrete MOPAs and flared unstable resonators have demonstrated the highest cw diffraction-limited output powers from semiconductor sources at wavelengths from 630 nm to beyond 2 μm. This talk will describe continuing advances in flared amplifier devices, including visible output powers approaching 1 W cw diffraction limited, powers up to 10 W diffraction-limited from monolithic devices, high-speed modulation, and more.","PeriodicalId":365685,"journal":{"name":"Semiconductor Lasers Advanced Devices and Applications","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115859422","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}
The spectral linewidth of a DFB laser increases significantly when directly modulated at a high frequency , a phenomenon known as frequency chirping . Means for reducing the frequency chirp have included the use of laser with a smaller linewidth enhancement factor of the active material and methods which reduce the spatial hole burning (SHB). The second approach involves fabrication of either complex laser structures which introduce gain coupling or quarter wavelength shift three section DFB lasers. We report here on the measurement of the frequency chirp of a two section DFB laser under large signal modulation . It was found that the frequency chirp of a two section laser can be minimized by simply adjusting the injection current distribution in the laser. The unique advantage for using two section DFB lasers is that frequency chirp can be reduced even when SHB is not suppressed.
{"title":"The Reduction of the Frequency Chirp of Two Section Distributed Feedback laser without Suppressing Spatial Hole Burning","authors":"J. Feng, T. Chen, B. Zhao, A. Yariv","doi":"10.1364/slada.1995.ma.4","DOIUrl":"https://doi.org/10.1364/slada.1995.ma.4","url":null,"abstract":"The spectral linewidth of a DFB laser increases significantly when directly modulated at a high frequency , a phenomenon known as frequency chirping . Means for reducing the frequency chirp have included the use of laser with a smaller linewidth enhancement factor of the active material and methods which reduce the spatial hole burning (SHB). The second approach involves fabrication of either complex laser structures which introduce gain coupling or quarter wavelength shift three section DFB lasers. We report here on the measurement of the frequency chirp of a two section DFB laser under large signal modulation . It was found that the frequency chirp of a two section laser can be minimized by simply adjusting the injection current distribution in the laser. The unique advantage for using two section DFB lasers is that frequency chirp can be reduced even when SHB is not suppressed.","PeriodicalId":365685,"journal":{"name":"Semiconductor Lasers Advanced Devices and Applications","volume":"169 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115917511","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 : 1900-01-01DOI: 10.1364/slada.1995.tua.1
T. Kurokawa, K. Nonaka
Photonic digital switches will be indispensable in future all-optical nodes for both time- and wavelength-division processing of optical signals for digital regeneration, Mux/Demux, and wavelength conversion. A bistable laser diode has the potential to achieve time- and wavelengh-divison processing simultaneously because it is inherently capable of digital regeneration due to its memory characteristics and of wavelength conversion when a side-injection structure is used [1,2]. This paper reports optical demultiplexing of 1 Gbps NRZ signals with simultaneous wavelengh conversion using a side-injection-light-controlled bistable laser diode (SILC-BLD) module with pigtailed fibers and a monitoring pin-photodiode.
{"title":"Simultaneous Demultiplexing and Wavelength Conversion of NRZ Optical Signals using a Side-Injection-Light-Controlled Bistable Laser Diode","authors":"T. Kurokawa, K. Nonaka","doi":"10.1364/slada.1995.tua.1","DOIUrl":"https://doi.org/10.1364/slada.1995.tua.1","url":null,"abstract":"Photonic digital switches will be indispensable in future all-optical nodes for both time- and wavelength-division processing of optical signals for digital regeneration, Mux/Demux, and wavelength conversion. A bistable laser diode has the potential to achieve time- and wavelengh-divison processing simultaneously because it is inherently capable of digital regeneration due to its memory characteristics and of wavelength conversion when a side-injection structure is used [1,2]. This paper reports optical demultiplexing of 1 Gbps NRZ signals with simultaneous wavelengh conversion using a side-injection-light-controlled bistable laser diode (SILC-BLD) module with pigtailed fibers and a monitoring pin-photodiode.","PeriodicalId":365685,"journal":{"name":"Semiconductor Lasers Advanced Devices and Applications","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116132622","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}
The usefulness of stimulated Raman transitions has been demonstrated in a variety of different applications. These two-photon transitions have the capability of very high resolution because the transition linewidths depend on the relative jitter between two frequencies, rather than absolute jitter on either one. Recent demonstrations include laser cooling and atomic interferometry [1]. They may also be needed for improved atomic clocks [2]. Due to this high resolution, stimulated Raman transitions can be a direct replacement for a microwave cavity and are often more compatible with optical experiments because a laser beam requires less space.
{"title":"Stimulated Raman Spectroscopy with a Modulated External Cavity Diode Laser","authors":"C. S. Wood, S. C. Bennett, D. Cho, C. Wieman","doi":"10.1364/slada.1995.mb.3","DOIUrl":"https://doi.org/10.1364/slada.1995.mb.3","url":null,"abstract":"The usefulness of stimulated Raman transitions has been demonstrated in a variety of different applications. These two-photon transitions have the capability of very high resolution because the transition linewidths depend on the relative jitter between two frequencies, rather than absolute jitter on either one. Recent demonstrations include laser cooling and atomic interferometry [1]. They may also be needed for improved atomic clocks [2]. Due to this high resolution, stimulated Raman transitions can be a direct replacement for a microwave cavity and are often more compatible with optical experiments because a laser beam requires less space.","PeriodicalId":365685,"journal":{"name":"Semiconductor Lasers Advanced Devices and Applications","volume":"299 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116255558","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 : 1900-01-01DOI: 10.1364/slada.1995.tuc.4
M. Krainak, D. Cornwell, Valerie Dutto, A. Yu, S. O’Brien
In this paper, we report on the optical spectrum characteristics of a modulated, high power (> 1 W average), monolithic flared amplifier master oscillator power amplifier (MFA-MOPA) laser. The CW performance of this laser is presented in Reference 1. The master oscillator (MO) is a distributed Bragg reflector (DBR) laser operating in a single longitudinal mode under CW operation. The power amplifier (PA) is monolithically integrated with the MO and has a tapered gain region. The laser was capable of delivering over 1 W of CW power with the MO biased at 140 mA and the PA biased at 4.0 A at operating temperature of 15°C. The MFA-MOPA can be tuned with temperature at a rate of 0.07 nm/°C. The instantaneous CW linewidth of the laser was measured to be 300 MHz (0.74 pm).
{"title":"Spectral Properties of an AlGaAs MOPA Laser Under Large Signal Modulation of the Oscillator or the Amplifier","authors":"M. Krainak, D. Cornwell, Valerie Dutto, A. Yu, S. O’Brien","doi":"10.1364/slada.1995.tuc.4","DOIUrl":"https://doi.org/10.1364/slada.1995.tuc.4","url":null,"abstract":"In this paper, we report on the optical spectrum characteristics of a modulated, high power (> 1 W average), monolithic flared amplifier master oscillator power amplifier (MFA-MOPA) laser. The CW performance of this laser is presented in Reference 1. The master oscillator (MO) is a distributed Bragg reflector (DBR) laser operating in a single longitudinal mode under CW operation. The power amplifier (PA) is monolithically integrated with the MO and has a tapered gain region. The laser was capable of delivering over 1 W of CW power with the MO biased at 140 mA and the PA biased at 4.0 A at operating temperature of 15°C. The MFA-MOPA can be tuned with temperature at a rate of 0.07 nm/°C. The instantaneous CW linewidth of the laser was measured to be 300 MHz (0.74 pm).","PeriodicalId":365685,"journal":{"name":"Semiconductor Lasers Advanced Devices and Applications","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124830380","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 : 1900-01-01DOI: 10.1364/slada.1995.tud.4
G. Yang, M. MacDougal, P. Dapkus
Vertical-cavity surface-emitting lasers (VCSEL's) fabricated by selective oxidation are attractive to achieve ultralow threshold currents [1-3]. Efficient heat dissipation, along with low threshold, is critical for uses as optical interconnects where massive integration is required. In this paper, we report an ultralow threshold of 8.7 µA and a high output power over 1.9 mW in single quantum well VCSEL's fabricated by selective oxidation from an all epitaxial structure with intracavity p-contact layers grown by metalorganic chemical vapor deposition. The design of this structure is optimized for low thermal resistance by using distributed Bragg reflectors (DBR's) composed completely of binary materials. Fig.l shows a schematic cross-section of the fabricated VCSEL's. The epitaxial structure consists of a 30-pair n-doped AlAs/GaAs quarter-wave stacks, an Al0.22Ga0.78As/GaAs/In0.2Ga0.8As resonant λ-cavity, p-doped contact layers, and a 22-pair undoped AlAs/GaAs quarter-wave stacks. The p-doped contact layers are formed from a 0.25 λ AlAs current constriction layer and a 0.75 λ GaAs intracavity contact layer. After growth, the top DBR is selectively wet etched into 14 and 5 µm square mesas down to the p-type GaAs contact layer. Then, 50 µm square mesas, whose centers coincide with the centers of the top mesas, are formed by wet chemical etching. Current flow apertures of 10 and ~3 µm are formed below the 14 and 5 µm square top mirrors, respectively, by selective oxidation.
{"title":"Low threshold current vertical-cavity surface-emitting lasers with enhanced resistance to heating","authors":"G. Yang, M. MacDougal, P. Dapkus","doi":"10.1364/slada.1995.tud.4","DOIUrl":"https://doi.org/10.1364/slada.1995.tud.4","url":null,"abstract":"Vertical-cavity surface-emitting lasers (VCSEL's) fabricated by selective oxidation are attractive to achieve ultralow threshold currents [1-3]. Efficient heat dissipation, along with low threshold, is critical for uses as optical interconnects where massive integration is required. In this paper, we report an ultralow threshold of 8.7 µA and a high output power over 1.9 mW in single quantum well VCSEL's fabricated by selective oxidation from an all epitaxial structure with intracavity p-contact layers grown by metalorganic chemical vapor deposition. The design of this structure is optimized for low thermal resistance by using distributed Bragg reflectors (DBR's) composed completely of binary materials. Fig.l shows a schematic cross-section of the fabricated VCSEL's. The epitaxial structure consists of a 30-pair n-doped AlAs/GaAs quarter-wave stacks, an Al0.22Ga0.78As/GaAs/In0.2Ga0.8As resonant λ-cavity, p-doped contact layers, and a 22-pair undoped AlAs/GaAs quarter-wave stacks. The p-doped contact layers are formed from a 0.25 λ AlAs current constriction layer and a 0.75 λ GaAs intracavity contact layer. After growth, the top DBR is selectively wet etched into 14 and 5 µm square mesas down to the p-type GaAs contact layer. Then, 50 µm square mesas, whose centers coincide with the centers of the top mesas, are formed by wet chemical etching. Current flow apertures of 10 and ~3 µm are formed below the 14 and 5 µm square top mirrors, respectively, by selective oxidation.","PeriodicalId":365685,"journal":{"name":"Semiconductor Lasers Advanced Devices and Applications","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117058061","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}
A. Stanton, D. S. Bomse, J. A. Silver, D. Hovde, D. Kane, D. Oh, M. Paige
Visible/near-infrared diode lasers are well-suited for use as spectroscopic light sources in detection of a wide variety of gases by measurement of optical absorption. The high spectral resolution of these devices permits the selective detection of targeted species, while their characteristics of relatively low cost, room temperature operation, and compatibility with fiber optics make them attractive for instrument development. The nominal range of available wavelengths (presently ~0.63 −~2.0 μm for commercially available devices that operate at room temperature) includes absorption bands of numerous gas species that need to be monitored to meet various industrial objectives (e.g. process control, emissions monitoring, toxic gas detection, etc.) While the molecular absorption bands in this spectral region consist mostly of relatively weak overtone or combination bands (some electronic bands are accessible at the shorter wavelengths), detection sensitivities of about 1 ppm-meter or better can be achieved for many gases using frequency or wavelength modulation techniques that permit routine measurement of small optical absorbances.1-2 Sub-ppm measurement sensitivities are easily achieved using simple optical multipass designs if necessary. A partial list of industrially significant gases that may be measured by this approach includes oxygen, water vapor, methane, acetylene, carbon monoxide, carbon dioxide, hydrogen halides, ammonia, hydrogen sulfide, and nitrogen oxides (both NO and NO2). Diode laser- based instruments for measurement of some of these species in process control or environmental monitoring applications are now commercially available.
{"title":"Diode Lasers for Industrial Spectroscopy","authors":"A. Stanton, D. S. Bomse, J. A. Silver, D. Hovde, D. Kane, D. Oh, M. Paige","doi":"10.1364/slada.1995.mb.1","DOIUrl":"https://doi.org/10.1364/slada.1995.mb.1","url":null,"abstract":"Visible/near-infrared diode lasers are well-suited for use as spectroscopic light sources in detection of a wide variety of gases by measurement of optical absorption. The high spectral resolution of these devices permits the selective detection of targeted species, while their characteristics of relatively low cost, room temperature operation, and compatibility with fiber optics make them attractive for instrument development. The nominal range of available wavelengths (presently ~0.63 −~2.0 μm for commercially available devices that operate at room temperature) includes absorption bands of numerous gas species that need to be monitored to meet various industrial objectives (e.g. process control, emissions monitoring, toxic gas detection, etc.) While the molecular absorption bands in this spectral region consist mostly of relatively weak overtone or combination bands (some electronic bands are accessible at the shorter wavelengths), detection sensitivities of about 1 ppm-meter or better can be achieved for many gases using frequency or wavelength modulation techniques that permit routine measurement of small optical absorbances.1-2 Sub-ppm measurement sensitivities are easily achieved using simple optical multipass designs if necessary. A partial list of industrially significant gases that may be measured by this approach includes oxygen, water vapor, methane, acetylene, carbon monoxide, carbon dioxide, hydrogen halides, ammonia, hydrogen sulfide, and nitrogen oxides (both NO and NO2). Diode laser- based instruments for measurement of some of these species in process control or environmental monitoring applications are now commercially available.","PeriodicalId":365685,"journal":{"name":"Semiconductor Lasers Advanced Devices and Applications","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116889607","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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