A. Utrilla, J. M. Ulloa, Ž. Gačević, D. Reyes, D. González, T. Ben, A. Guzmán, A. Hierro
In this manuscript we carry out a comparative analysis of p-i-n junction solar cells based on 10 stacks of InAs/GaAs quantum dots (QDs) capped with GaAs(Sb)(N) capping layers (CLs). The application of such CLs allows to significantly extend the photoresponse beyond 1.3 μm. Moreover, a strong photocurrent from the CLs is observed so that the devices work as QD-quantum well solar cells. The GaAsSb CL leads to the best results, providing a strong sub-band-gap contribution, which is higher than that in a sample containing standard GaAs-capped QDs, despite giving rise to the highest accumulated strain. The use of a GaAsN CL reduces the photocurrent originating from GaAs, pointing to electron retrapping and hindered extraction and/or the introduction of point defects as possible reasons for this. Nevertheless, the addition of N helps to balance the accumulated strain, necessary to stack a higher number of QD layers. In addition, the possibility to independently tune the hole and electron confinements by the simultaneous presence of Sb and N in the CL is also confirmed for 10 stacked QD layers. This not only allows to further extend the QD ground state and, therefore, the photoresponse, but also offers the possibility to design an optimized structure facilitating carrier extraction from the QDs. Nevertheless, carrier losses seem to be stronger under the simultaneous presence of N and Sb in the CL.
{"title":"Stacked GaAs(Sb)(N)-capped InAs/GaAs quantum dots for enhanced solar cell efficiency","authors":"A. Utrilla, J. M. Ulloa, Ž. Gačević, D. Reyes, D. González, T. Ben, A. Guzmán, A. Hierro","doi":"10.1117/12.2077151","DOIUrl":"https://doi.org/10.1117/12.2077151","url":null,"abstract":"In this manuscript we carry out a comparative analysis of p-i-n junction solar cells based on 10 stacks of InAs/GaAs quantum dots (QDs) capped with GaAs(Sb)(N) capping layers (CLs). The application of such CLs allows to significantly extend the photoresponse beyond 1.3 μm. Moreover, a strong photocurrent from the CLs is observed so that the devices work as QD-quantum well solar cells. The GaAsSb CL leads to the best results, providing a strong sub-band-gap contribution, which is higher than that in a sample containing standard GaAs-capped QDs, despite giving rise to the highest accumulated strain. The use of a GaAsN CL reduces the photocurrent originating from GaAs, pointing to electron retrapping and hindered extraction and/or the introduction of point defects as possible reasons for this. Nevertheless, the addition of N helps to balance the accumulated strain, necessary to stack a higher number of QD layers. In addition, the possibility to independently tune the hole and electron confinements by the simultaneous presence of Sb and N in the CL is also confirmed for 10 stacked QD layers. This not only allows to further extend the QD ground state and, therefore, the photoresponse, but also offers the possibility to design an optimized structure facilitating carrier extraction from the QDs. Nevertheless, carrier losses seem to be stronger under the simultaneous presence of N and Sb in the CL.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122136811","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 novel photonic analog-to-binary converter based on the first-order asynchronous delta-sigma modulation (ADSM) has been theoretically investigated and experimentally demonstrated. A fiber-optic prototype ADSM system is constructed and characterized. Delta-sigma modulation is a straightforward approach to A/D conversion because in this case an external clocking is not required and demodulation can be simply performed via a low-pass filtering process. To improve signal-to-noise ratio and thus system ENOB, a non-interferometric optical implementation has been constructed. The ADSM is comprised of three photonic devices: an inverted output photonic leaky integrator, bistable quantizer, and positive corrective feedback. The photonic integrator which is a recirculating loop performs the oversampling of an analog input using the cross-gain modulation in an SOA. We will show that the photonic ADSM produces an inverted non-return-to-zero (NRZ) pulse-density modulated output describing an input analog signal. This fiber-optic ADSM converts up to 7.6 MHz analog input at about 30 MS/s and effective ENOB of 6.
{"title":"Fiber-optic analog-to-NRZ binary conversion","authors":"A. Siahmakoun, E. Reeves","doi":"10.1117/12.2080074","DOIUrl":"https://doi.org/10.1117/12.2080074","url":null,"abstract":"A novel photonic analog-to-binary converter based on the first-order asynchronous delta-sigma modulation (ADSM) has been theoretically investigated and experimentally demonstrated. A fiber-optic prototype ADSM system is constructed and characterized. Delta-sigma modulation is a straightforward approach to A/D conversion because in this case an external clocking is not required and demodulation can be simply performed via a low-pass filtering process. To improve signal-to-noise ratio and thus system ENOB, a non-interferometric optical implementation has been constructed. The ADSM is comprised of three photonic devices: an inverted output photonic leaky integrator, bistable quantizer, and positive corrective feedback. The photonic integrator which is a recirculating loop performs the oversampling of an analog input using the cross-gain modulation in an SOA. We will show that the photonic ADSM produces an inverted non-return-to-zero (NRZ) pulse-density modulated output describing an input analog signal. This fiber-optic ADSM converts up to 7.6 MHz analog input at about 30 MS/s and effective ENOB of 6.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116825848","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}
Tae-Ryong Kim, H. Kim, Jun Li, G. Oh, Doo-Gun Kim, Young-Wan Choi
In this paper, surface plasmon resonance triangular ring resonator (SPR-TRR) Vernier structure based on InP is simulated for index variation from 1.33 to 1.35. Sensing area of SPR-TRR is achieved to make an ultra-compact SPR mirror by deposition of Au film layer which is designed to deposit on vertex of TRR. The possibility of mass production is shown by a deposition of SPR mirror on the triangular ring resonator (TRR). Also, the sensitivity enhancement of an envelope signal for Vernier effect is confirmed by FDTD simulation compared to SPR-TRR. As simulation results, the sensitivity is enhanced 20 nm / RIU to 480 nm / RIU. Thus, SPR-TRR Vernier structure is used for a biosensor to enhance the sensitivity of biosensor.
{"title":"Ultra-high sensitivity optical biosensor based on Vernier effect in triangular ring resonators (TRRs) with SPR","authors":"Tae-Ryong Kim, H. Kim, Jun Li, G. Oh, Doo-Gun Kim, Young-Wan Choi","doi":"10.1117/12.2078923","DOIUrl":"https://doi.org/10.1117/12.2078923","url":null,"abstract":"In this paper, surface plasmon resonance triangular ring resonator (SPR-TRR) Vernier structure based on InP is simulated for index variation from 1.33 to 1.35. Sensing area of SPR-TRR is achieved to make an ultra-compact SPR mirror by deposition of Au film layer which is designed to deposit on vertex of TRR. The possibility of mass production is shown by a deposition of SPR mirror on the triangular ring resonator (TRR). Also, the sensitivity enhancement of an envelope signal for Vernier effect is confirmed by FDTD simulation compared to SPR-TRR. As simulation results, the sensitivity is enhanced 20 nm / RIU to 480 nm / RIU. Thus, SPR-TRR Vernier structure is used for a biosensor to enhance the sensitivity of biosensor.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129859764","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 optical and electrical properties of a photonic-plasmonic nanostructure on the back contact of thin-film solar cells were investigated numerically through the three-dimensional (3D) finite-difference time-domain method and the 3D Poisson and drift-diffusion solver. The focusing effect and the Fabry-Perot resonances are identified as the main mechanisms for the enhancement of the optical generation rate as well as the short circuit current density. However, the surface topography of certain nanopattern structures is found to reduce the internal electrostatic field of the device, thus limiting charge collection. The optimized conditions for both optics and electronics have been analyzed in this paper.
{"title":"Design of nano-pattern reflectors for thin-film solar cells based on three-dimensional optical and electrical modeling","authors":"H. Hsiao, H. C. Chang, Y. R. Wu","doi":"10.1117/12.2079582","DOIUrl":"https://doi.org/10.1117/12.2079582","url":null,"abstract":"The optical and electrical properties of a photonic-plasmonic nanostructure on the back contact of thin-film solar cells were investigated numerically through the three-dimensional (3D) finite-difference time-domain method and the 3D Poisson and drift-diffusion solver. The focusing effect and the Fabry-Perot resonances are identified as the main mechanisms for the enhancement of the optical generation rate as well as the short circuit current density. However, the surface topography of certain nanopattern structures is found to reduce the internal electrostatic field of the device, thus limiting charge collection. The optimized conditions for both optics and electronics have been analyzed in this paper.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128498243","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}
Significant development work has been completed in recent years to improve experimental results reaching a record efficiency of 9.14% under one sun AM0 conditions with no anti-reflection coating. The nipi solar cell utilizes epitaxial regrowth contacts to ensure carrier selective contacts to the alternating n and p-type doped layers, forming selectively ohmic and rectifying contacts. Defects or traps formed in the rectifying contact during the epitaxial regrowth process result in injected current that contributes directly to dark current. As a result detailed characterization of the epitaxial regrowth interface is required to understand and minimize the formation of interface traps. Concentration measurements have been completed to characterize the trap states impact on efficiency as higher concentration results in state filling and a recovery in open circuit voltage. A model has been developed to gain further understanding of the measurements under concentration.
{"title":"Modeling nipi solar cells under concentration accounting for state filling effects","authors":"M. Slocum, D. Forbes, S. Hubbard","doi":"10.1117/12.2081039","DOIUrl":"https://doi.org/10.1117/12.2081039","url":null,"abstract":"Significant development work has been completed in recent years to improve experimental results reaching a record efficiency of 9.14% under one sun AM0 conditions with no anti-reflection coating. The nipi solar cell utilizes epitaxial regrowth contacts to ensure carrier selective contacts to the alternating n and p-type doped layers, forming selectively ohmic and rectifying contacts. Defects or traps formed in the rectifying contact during the epitaxial regrowth process result in injected current that contributes directly to dark current. As a result detailed characterization of the epitaxial regrowth interface is required to understand and minimize the formation of interface traps. Concentration measurements have been completed to characterize the trap states impact on efficiency as higher concentration results in state filling and a recovery in open circuit voltage. A model has been developed to gain further understanding of the measurements under concentration.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129576108","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}
N. Ledentsov, V. Shchukin, M. Maximov, N. Gordeev, N. Kaluzhniy, S. Mintairov, A. Payusov, Y. Shernyakov, K. A. Vashanova, M. Kulagina, N. Schmidt
Ultralarge output apertures of semiconductor gain chips facilitate novel applications that require efficient feedback of the reflected laser light. Thick (10-30 μm) and ultrabroad (>1000 μm) waveguides are suitable for coherent coupling through both near-field of the neighboring stripes in a laser bar and by applying external cavities. As a result direct laser diodes may become suitable as high-power high-brightness coherent light sources. Passive cavity laser is based on the idea of placing the active media outside of the main waveguide, for example in the cladding layers attached to the waveguide, or, as in the case of the Tilted Wave Laser (TWL) in a thin waveguide coupled to the neighboring thick waveguide wherein most of the field intensity is localized in the broad waveguide. Multimode or a single vertical mode lasing is possible depending on the coupling efficiency. We demonstrate that 1060 nm GaAs/GaAlAs–based Tilted Wave Lasers (TWL) show wall-plug efficiency up to ~55% with the power concentrated in the two symmetric vertical beams having a full width at half maximum (FWHM) of 2 degrees each. Bars with pitch sizes in the range of 25–400 μm are studied and coherent operation of the bars is manifested with the lateral far field lobes as narrow as 0.1° FWHM. As the near field of such lasers in the vertical direction represents a strongly modulated highly periodic pattern of intensity maxima such lasers or laser arrays generate Bessel-type beams. These beams are focusable similar to the case of Gaussian beams. However, opposite to the Gaussian beams, such beams are self-healing and quasi non-divergent. Previously Bessel beams were generated using Gaussian beams in combination with an axicon lens or a Fresnel biprism. A new approach does not involve such complexity and a novel generation of laser diodes evolves.
{"title":"Passive cavity laser and tilted wave laser for Bessel-like beam coherently coupled bars and stacks","authors":"N. Ledentsov, V. Shchukin, M. Maximov, N. Gordeev, N. Kaluzhniy, S. Mintairov, A. Payusov, Y. Shernyakov, K. A. Vashanova, M. Kulagina, N. Schmidt","doi":"10.1117/12.2077018","DOIUrl":"https://doi.org/10.1117/12.2077018","url":null,"abstract":"Ultralarge output apertures of semiconductor gain chips facilitate novel applications that require efficient feedback of the reflected laser light. Thick (10-30 μm) and ultrabroad (>1000 μm) waveguides are suitable for coherent coupling through both near-field of the neighboring stripes in a laser bar and by applying external cavities. As a result direct laser diodes may become suitable as high-power high-brightness coherent light sources. Passive cavity laser is based on the idea of placing the active media outside of the main waveguide, for example in the cladding layers attached to the waveguide, or, as in the case of the Tilted Wave Laser (TWL) in a thin waveguide coupled to the neighboring thick waveguide wherein most of the field intensity is localized in the broad waveguide. Multimode or a single vertical mode lasing is possible depending on the coupling efficiency. We demonstrate that 1060 nm GaAs/GaAlAs–based Tilted Wave Lasers (TWL) show wall-plug efficiency up to ~55% with the power concentrated in the two symmetric vertical beams having a full width at half maximum (FWHM) of 2 degrees each. Bars with pitch sizes in the range of 25–400 μm are studied and coherent operation of the bars is manifested with the lateral far field lobes as narrow as 0.1° FWHM. As the near field of such lasers in the vertical direction represents a strongly modulated highly periodic pattern of intensity maxima such lasers or laser arrays generate Bessel-type beams. These beams are focusable similar to the case of Gaussian beams. However, opposite to the Gaussian beams, such beams are self-healing and quasi non-divergent. Previously Bessel beams were generated using Gaussian beams in combination with an axicon lens or a Fresnel biprism. A new approach does not involve such complexity and a novel generation of laser diodes evolves.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130802857","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}
P. Liu, F. Valmorra, C. Maissen, J. Keller, G. Scalari, J. Faist
We design and experimentally investigate various large-area gate-tunable terahertz plasmonic metasurfaces employing different types of graphene based structures, i.e. arrays of graphene ribbons, square-lattice graphene anti-dots and hexagonal-lattice graphene anti-dots. Distinct gate-tunable resonances in the terahertz frequency range arising from excitations of plasmonic resonance modes associated with different structures are observed in their transmission spectra. Carrier density dependent tuning of the resonance frequency exhibits excellent agreement with the theoretical prediction and the numerical simulation. The demonstrated graphene based terahertz plasmonic metasurfaces can be employed to realize more complex devices and functionalities such as tunable plasmonic waveguide and transformation optics.
{"title":"Large-area gate-tunable terahertz plasmonic metasurfaces employing graphene based structures","authors":"P. Liu, F. Valmorra, C. Maissen, J. Keller, G. Scalari, J. Faist","doi":"10.1117/12.2083108","DOIUrl":"https://doi.org/10.1117/12.2083108","url":null,"abstract":"We design and experimentally investigate various large-area gate-tunable terahertz plasmonic metasurfaces employing different types of graphene based structures, i.e. arrays of graphene ribbons, square-lattice graphene anti-dots and hexagonal-lattice graphene anti-dots. Distinct gate-tunable resonances in the terahertz frequency range arising from excitations of plasmonic resonance modes associated with different structures are observed in their transmission spectra. Carrier density dependent tuning of the resonance frequency exhibits excellent agreement with the theoretical prediction and the numerical simulation. The demonstrated graphene based terahertz plasmonic metasurfaces can be employed to realize more complex devices and functionalities such as tunable plasmonic waveguide and transformation optics.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125469865","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}
G. Sokolovskii, V. Dudelev, E. D. Kolykhalova, K. Soboleva, A. G. Deryagin, I. Novikov, M. V. Maximov, A. E. Zhukov, V. Ustinov, V. Kuchinskii, W. Sibbett, E. Rafailov, E. Viktorov, T. Erneux
We study InGaAs QD laser operating simultaneously at ground (GS) and excited (ES) states under 30ns pulsed-pumping and distinguish three regimes of operation depending on the pump current and the carrier relaxation pathways. An increased current leads to an increase in ES intensity and to a decrease in GS intensity (or saturation) for low pump range, as typical for the cascade-like pathway. Both the GS and ES intensities are steadily increased for high current ranges, which prove the dominance of the direct capture pathway. The relaxation oscillations are not pronounced for these ranges. For the mediate currents, the interplay between the both pathways leads to the damped large amplitude relaxation oscillations with significant deviation of the relaxation oscillation frequency from the initial value during the pulse.
{"title":"Impact of the carrier relaxation paths on two-state operation in quantum dot lasers","authors":"G. Sokolovskii, V. Dudelev, E. D. Kolykhalova, K. Soboleva, A. G. Deryagin, I. Novikov, M. V. Maximov, A. E. Zhukov, V. Ustinov, V. Kuchinskii, W. Sibbett, E. Rafailov, E. Viktorov, T. Erneux","doi":"10.1117/12.2078746","DOIUrl":"https://doi.org/10.1117/12.2078746","url":null,"abstract":"We study InGaAs QD laser operating simultaneously at ground (GS) and excited (ES) states under 30ns pulsed-pumping and distinguish three regimes of operation depending on the pump current and the carrier relaxation pathways. An increased current leads to an increase in ES intensity and to a decrease in GS intensity (or saturation) for low pump range, as typical for the cascade-like pathway. Both the GS and ES intensities are steadily increased for high current ranges, which prove the dominance of the direct capture pathway. The relaxation oscillations are not pronounced for these ranges. For the mediate currents, the interplay between the both pathways leads to the damped large amplitude relaxation oscillations with significant deviation of the relaxation oscillation frequency from the initial value during the pulse.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126690261","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}
Microwave frequency combs utilizing hybrid optical injections schemes by varying the operational parameters, injection strength, repetition frequency, and detuning frequency are demonstrated and characterized. The dynamical hybrid optical injections are realized by both optical pulse injection and optical cw injection to the slave laser simultaneously under the condition of zero detuning frequency between two injecting source lasers. For pure pulse injection case, the amplitude variation of ±27.3 dB in a 30 GHz range is obtained. By further applying the injection strength of the cw injection to the pulses injected semiconductor laser, the amplitude variation of ±3.3 dB in a 30 GHz range in microwave frequency combs are observed when operating the cw injection system in a stable locking state. In order to examine the microwave frequency comb precisely, each operational parameters of the hybrid optical injections schemes are analyzed. The amplitude variation of microwave frequency combs is also strongly influenced by operating the cw injection system in different states. Comparing to the cw injection system operated in period-one states, the amplitude variation is reduced when operated in the stable locking states. Moreover, the bandwidth broadening in microwave frequency comb is expected when the cw injection system operating in a stable locking state. In this paper, strongly improve the amplitude variation of the microwave frequency combs generated utilizing hybrid injections scheme compared to single injection case are obtained and compared.
{"title":"Analysis of microwave frequency combs generated by semiconductor lasers under hybrid optical injections","authors":"Cheng-Ting Lin, Yi-Hua Wu, Y. Juan","doi":"10.1117/12.2078864","DOIUrl":"https://doi.org/10.1117/12.2078864","url":null,"abstract":"Microwave frequency combs utilizing hybrid optical injections schemes by varying the operational parameters, injection strength, repetition frequency, and detuning frequency are demonstrated and characterized. The dynamical hybrid optical injections are realized by both optical pulse injection and optical cw injection to the slave laser simultaneously under the condition of zero detuning frequency between two injecting source lasers. For pure pulse injection case, the amplitude variation of ±27.3 dB in a 30 GHz range is obtained. By further applying the injection strength of the cw injection to the pulses injected semiconductor laser, the amplitude variation of ±3.3 dB in a 30 GHz range in microwave frequency combs are observed when operating the cw injection system in a stable locking state. In order to examine the microwave frequency comb precisely, each operational parameters of the hybrid optical injections schemes are analyzed. The amplitude variation of microwave frequency combs is also strongly influenced by operating the cw injection system in different states. Comparing to the cw injection system operated in period-one states, the amplitude variation is reduced when operated in the stable locking states. Moreover, the bandwidth broadening in microwave frequency comb is expected when the cw injection system operating in a stable locking state. In this paper, strongly improve the amplitude variation of the microwave frequency combs generated utilizing hybrid injections scheme compared to single injection case are obtained and compared.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115261325","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}
Y. Murakami, Katsuya Arai, M. Wakaki, T. Shibuya, T. Shintaku
Photodoping phenomenon is observed when a double-layer consisting of an amorphous chalcogenide film (As2S3, GeS2, GeSe2 etc.) and a metal (Ag, Cu etc.) film is illuminated by light. The metal diffuses abnormally into the amorphous chalcogenide layer. Amorphous chalcogenide films of GeS2 with an Ag over layer exhibited large increase of refractive index through the abnormal doping of Ag by irradiating the light around the absorption edge of the GeS2 chalcogenide. In this study, we aimed the application of this effect for the fabrication of optical devices and fabricated various micro doped patterns by using a laser beam. Mask less pattering with refractive index modified films are possible by manipulating the scanning of the laser beam. Micro gratings were fabricated using a confocal laser microscope to work as both fabrication and observation system. Waveguides were also fabricated by scanning the laser beam for photodoping. Holographic gratings were fabricated by utilizing the photodoping of the two beam interference pattern, which showed the possibility to produce large scale optical devices or mass production.
{"title":"Application of photo-doping phenomenon in amorphous chalcogenide GeS2 film to optical device","authors":"Y. Murakami, Katsuya Arai, M. Wakaki, T. Shibuya, T. Shintaku","doi":"10.1117/12.2078142","DOIUrl":"https://doi.org/10.1117/12.2078142","url":null,"abstract":"Photodoping phenomenon is observed when a double-layer consisting of an amorphous chalcogenide film (As2S3, GeS2, GeSe2 etc.) and a metal (Ag, Cu etc.) film is illuminated by light. The metal diffuses abnormally into the amorphous chalcogenide layer. Amorphous chalcogenide films of GeS2 with an Ag over layer exhibited large increase of refractive index through the abnormal doping of Ag by irradiating the light around the absorption edge of the GeS2 chalcogenide. In this study, we aimed the application of this effect for the fabrication of optical devices and fabricated various micro doped patterns by using a laser beam. Mask less pattering with refractive index modified films are possible by manipulating the scanning of the laser beam. Micro gratings were fabricated using a confocal laser microscope to work as both fabrication and observation system. Waveguides were also fabricated by scanning the laser beam for photodoping. Holographic gratings were fabricated by utilizing the photodoping of the two beam interference pattern, which showed the possibility to produce large scale optical devices or mass production.","PeriodicalId":432115,"journal":{"name":"Photonics West - Optoelectronic Materials and Devices","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121494058","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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