Pub Date : 1994-07-06DOI: 10.1109/LEOSST.1994.700533
E. Larkins, W. Rothemund, J. Wagner, M. Baeumier, S. Burkner, W. Benz, S. Weisser, A. Schonfelder, G. Flemig, R. Brenn, J. Fleissner, W. Jantz, J. Rosenzweig, J. Ralston
Pseudomorphic InyGal-yAs/GaAs/AlxGal.xAs MQW lasers are receiving increasing attention for shorthaul, high-speed data transmission, because they have much larger modulation bandwidths1 and smaller linewidth enhancement factors2 than GaAs/AlGaAs lasers. Although pseudomorphic InGaAs/GaAs technology is relatively young, lasers fabricated in this material system have already achieved larger direct modulation bandwidths (33 GHz at 65 mA 3, than any other material system. The key processes influencing the MBE growth of pseudomorphically strained InGaAs/GaAs/AlGaAs structures are only now being identified4p5. Thus, the growth of such structures has followed a "trial and error" approach, based on experience from the growth of GaAs/AIGaAs heterostructures. For GaAs/AlGaAs lasers, it was shown that higher substrate temperatures improved the AlGaAs quality and reduce the threshold current densities6. For pseudomorphic MQW lasers, it became necessary to grow two different ternary alloys, whose independently optimized growth parameters are quite different. As a result, it has become common practice to optimize the InyGal.yAs, GaAs and AI,Gal.,As growth parameters independently7. Such independent optimization presumes that the growth of each layer does not significantly influence the other layers a presumption which becomes questionable for the larger strains and stresses associated with the newest generation of pseudomorphic diode lasers. In this paper, we present the most recent results of our on-going investigation into the MBE growth processes of pseudomorphically strained InyGal.yAs. We present compelling evidence showing that the quality of InGaAs/GaAs MQWs in such lasers depends strongly on the growth parameters of the other epitaxial layers particularly on the AlGaAs growth temperature. This interdependence forces a complete re-evaluation of the appropriateness of I n G W G a A s growth protocols based on unstrained GaAs/AlGaAs MBE growth processes. As-grown and annealed In0.35Ga0.65As/GaAs test structures and diode lasers have been extensivel! characterized with resonant Raman scattering, photoluminescence (PL), PL microscopy (PLM) and ion channeling. We observe a gradual onset for strain relaxation through the formation of -oriented dislocations and oriented line defects. The formation and propagation of both misfit dislocations and line defects depends strongly on i) the growth temperature, ii) the substrate quality, iii) the total number of QWs. iv) the thickness of the QW barrier layers, and v) the impurity (e.g dopant) concentration in these barriers. Ion channeling measurements and annealing studies reveal increasing structural instability of the MQW structures as the number of QWs increases. The formation of misfit dislocations and line defects ispreceded by the incorporation of as yet unidentified point defects. Resonant Raman measurements (Fig. 1) show an increase in the intensity of 1-LO phonon scattering from the GaAs barriers with increas
{"title":"MBE Growth Of GaAs-based Pseudomorphic Lasers: Key Growth Trade-offs Between The InGaAs MQWs And The AlGaAs Cladding","authors":"E. Larkins, W. Rothemund, J. Wagner, M. Baeumier, S. Burkner, W. Benz, S. Weisser, A. Schonfelder, G. Flemig, R. Brenn, J. Fleissner, W. Jantz, J. Rosenzweig, J. Ralston","doi":"10.1109/LEOSST.1994.700533","DOIUrl":"https://doi.org/10.1109/LEOSST.1994.700533","url":null,"abstract":"Pseudomorphic InyGal-yAs/GaAs/AlxGal.xAs MQW lasers are receiving increasing attention for shorthaul, high-speed data transmission, because they have much larger modulation bandwidths1 and smaller linewidth enhancement factors2 than GaAs/AlGaAs lasers. Although pseudomorphic InGaAs/GaAs technology is relatively young, lasers fabricated in this material system have already achieved larger direct modulation bandwidths (33 GHz at 65 mA 3, than any other material system. The key processes influencing the MBE growth of pseudomorphically strained InGaAs/GaAs/AlGaAs structures are only now being identified4p5. Thus, the growth of such structures has followed a \"trial and error\" approach, based on experience from the growth of GaAs/AIGaAs heterostructures. For GaAs/AlGaAs lasers, it was shown that higher substrate temperatures improved the AlGaAs quality and reduce the threshold current densities6. For pseudomorphic MQW lasers, it became necessary to grow two different ternary alloys, whose independently optimized growth parameters are quite different. As a result, it has become common practice to optimize the InyGal.yAs, GaAs and AI,Gal.,As growth parameters independently7. Such independent optimization presumes that the growth of each layer does not significantly influence the other layers a presumption which becomes questionable for the larger strains and stresses associated with the newest generation of pseudomorphic diode lasers. In this paper, we present the most recent results of our on-going investigation into the MBE growth processes of pseudomorphically strained InyGal.yAs. We present compelling evidence showing that the quality of InGaAs/GaAs MQWs in such lasers depends strongly on the growth parameters of the other epitaxial layers particularly on the AlGaAs growth temperature. This interdependence forces a complete re-evaluation of the appropriateness of I n G W G a A s growth protocols based on unstrained GaAs/AlGaAs MBE growth processes. As-grown and annealed In0.35Ga0.65As/GaAs test structures and diode lasers have been extensivel! characterized with resonant Raman scattering, photoluminescence (PL), PL microscopy (PLM) and ion channeling. We observe a gradual onset for strain relaxation through the formation of -oriented dislocations and oriented line defects. The formation and propagation of both misfit dislocations and line defects depends strongly on i) the growth temperature, ii) the substrate quality, iii) the total number of QWs. iv) the thickness of the QW barrier layers, and v) the impurity (e.g dopant) concentration in these barriers. Ion channeling measurements and annealing studies reveal increasing structural instability of the MQW structures as the number of QWs increases. The formation of misfit dislocations and line defects ispreceded by the incorporation of as yet unidentified point defects. Resonant Raman measurements (Fig. 1) show an increase in the intensity of 1-LO phonon scattering from the GaAs barriers with increas","PeriodicalId":379594,"journal":{"name":"Proceedings of IEE/LEOS Summer Topical Meetings: Integrated Optoelectronics","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127692625","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 : 1994-07-06DOI: 10.1109/LEOSST.1994.700546
T. D. Mousakas
{"title":"Growth And Properties Of GaN Produced By ECR-MBE","authors":"T. D. Mousakas","doi":"10.1109/LEOSST.1994.700546","DOIUrl":"https://doi.org/10.1109/LEOSST.1994.700546","url":null,"abstract":"","PeriodicalId":379594,"journal":{"name":"Proceedings of IEE/LEOS Summer Topical Meetings: Integrated Optoelectronics","volume":"42 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116728787","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 : 1994-07-06DOI: 10.1109/LEOSST.1994.700475
C. Mao, L. Ji, D. McKnight, R. Feuerstein, J. Neff
{"title":"CMOS 2 X 8 Photoreceiver Array For Free Space Holographically Interconnected Counter","authors":"C. Mao, L. Ji, D. McKnight, R. Feuerstein, J. Neff","doi":"10.1109/LEOSST.1994.700475","DOIUrl":"https://doi.org/10.1109/LEOSST.1994.700475","url":null,"abstract":"","PeriodicalId":379594,"journal":{"name":"Proceedings of IEE/LEOS Summer Topical Meetings: Integrated Optoelectronics","volume":"125 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126174663","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 : 1994-07-06DOI: 10.1109/LEOSST.1994.700421
L. Coldren, V. Jayaraman
Prior to 1991, the most advanced tunable semiconductor laser was the “Distributed Bragg Reflector” or DBR laser. DBR lasers employ a cavity design which constrains the fractional wavelength tuning Ahlh to be no more than the achievable fractional index change Aplp in a semiconductor waveguide. The maximum fractional index shift is just under 1 %, resulting in maximum tuning ranges around 10 nm at 1.5 microns (pm). Since 1991, however, three different cavity geometries have been demonstrated, with much wider tuning ranges. Figure 1 shows the Y-cavity geometry [ 11, versions of which have demonstrated on the order of 50 nm tuning [ 1,2]. Figure 2 shows the grating-assisted co-directional coupler laser (GACC) [3], which has also demonstrated more than 50 nm tuning. Lastly, Fig. 3 shows the sampled grating DBR laser, which we describe in more detail below. The sampled grating laser was first proposed by us in 1990 [4], and demonstrated in 1991 [5]. As shown in Fig. 3, the device relies on two DBR gratings modulated by an on-off sampling function, resulting in periodic reflection spectra. The periods of the two mirrors are slightly mismatched, and lasing occurs where two mirror maxima are aligned. Tuning one mirror relative to the other causes the alignment position to shift to adjacent maxima, resulting in wide-range “vernier effect” tuning. Inducing identical index changes in both mirrors allows coverage between mirror maxima. Figures 4,5, and 6 show our most recent sampled grating DBR results [6]. Figure 4 shows 73 nm tuning with 62 nm continuous wave range. Figure 5 shows light-current properties. Figure 6 shows some continuous-wave spectra, indicating very large suppression of spurious mirror resonances. The sampled grating DBR laser has also been implemented using periodically chirped gratings. This approach has also resulted in very impressive results, with tuning ranges of up to 100 nm demonstrated [7].
{"title":"Tunable Lasers For Photonic Integrated Circuits","authors":"L. Coldren, V. Jayaraman","doi":"10.1109/LEOSST.1994.700421","DOIUrl":"https://doi.org/10.1109/LEOSST.1994.700421","url":null,"abstract":"Prior to 1991, the most advanced tunable semiconductor laser was the “Distributed Bragg Reflector” or DBR laser. DBR lasers employ a cavity design which constrains the fractional wavelength tuning Ahlh to be no more than the achievable fractional index change Aplp in a semiconductor waveguide. The maximum fractional index shift is just under 1 %, resulting in maximum tuning ranges around 10 nm at 1.5 microns (pm). Since 1991, however, three different cavity geometries have been demonstrated, with much wider tuning ranges. Figure 1 shows the Y-cavity geometry [ 11, versions of which have demonstrated on the order of 50 nm tuning [ 1,2]. Figure 2 shows the grating-assisted co-directional coupler laser (GACC) [3], which has also demonstrated more than 50 nm tuning. Lastly, Fig. 3 shows the sampled grating DBR laser, which we describe in more detail below. The sampled grating laser was first proposed by us in 1990 [4], and demonstrated in 1991 [5]. As shown in Fig. 3, the device relies on two DBR gratings modulated by an on-off sampling function, resulting in periodic reflection spectra. The periods of the two mirrors are slightly mismatched, and lasing occurs where two mirror maxima are aligned. Tuning one mirror relative to the other causes the alignment position to shift to adjacent maxima, resulting in wide-range “vernier effect” tuning. Inducing identical index changes in both mirrors allows coverage between mirror maxima. Figures 4,5, and 6 show our most recent sampled grating DBR results [6]. Figure 4 shows 73 nm tuning with 62 nm continuous wave range. Figure 5 shows light-current properties. Figure 6 shows some continuous-wave spectra, indicating very large suppression of spurious mirror resonances. The sampled grating DBR laser has also been implemented using periodically chirped gratings. This approach has also resulted in very impressive results, with tuning ranges of up to 100 nm demonstrated [7].","PeriodicalId":379594,"journal":{"name":"Proceedings of IEE/LEOS Summer Topical Meetings: Integrated Optoelectronics","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127345276","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 : 1994-07-06DOI: 10.1109/LEOSST.1994.700553
L. Eng, K. Toh, C. Chang-Hasnain, K. Bacher, J. Harris
Two dimensional multiple wavelength vertical cavity surface emitting laser (VCSEL) arrays are promising for ultrahigh capacity optical networks using wavelength division multiplexing (WDM). The emission wavelength of a VCSEL is determined by the laser cavity round trip phase condition, which can be varied across the array by varying the thickness of either the cavity or the dielectric mirror layers. In prior work, a 2D VCSEL array emitting 140 distinct wavelengths was reported [ 13 using a spatially tapered mirror layer in the VCSEL caused by the inherent beam flux gradient in a Molecluar Beam Epitaxy (MBE) system. In this work, we demonstrate an induced lateral variation in cavity thickness of a GaAs/AlAs Fabry Perot resonator. By indium bonding the substrate to patterned backing wafers we induce a lateral surface temperature gradient on the substrate, thereby altering the GaAs desorption rate across the wafer during the growth of the cavity. Above substrate temperatures of 640 C, the GaAs growth rate is a strongly decreasing function of temperature [2]. Previously, Goodhue et. al. achieved substrate surface temperature differences of 30 50 C by mounting the substrates, using indium, to molybdenum blocks machined with 1 mm deep grooves and a 10 mm period [3]. They observed a near 3 fold decrease in GaAs growth rate in the high temperature regions of the wafer. In our work we have used indium to selectively bond the GaAs substrate to GaAs wafers which have patterns ranging from 2 to 8 mm. The advantage of this technique is that we can define the patterns lithographically. We then grow passive Fabry Perot cavities consisting of AlAs/GaAs Bragg mirror stacks centered at 950 nm, 10.5 pairs on the bottom and 8 on the top, and a 300 nm thick GaAs cavity. The calculated cavity mode of this structure is 980 nm. Both mirrors are grown at a substrate temperature of 600 C and the cavity is grown at approximately 700 C. A schematic of this technique is shown in Figure 1. We expect the mirrors to be uniform since they are grown below the gallium desorption temperature. The cavity, however, will have a thickness variation across the wafer due to the induced surface temperature difference in a regime in which significant gallium desorption occurs. We characterize the material by measuring reflectivity spectra across the wafer, and mapping the Fabry Perot wavelength. The spatial resolution of the measurement is 100 pm. Figure 2 shows the measured cavity mode position perpendicular to the direction of a single 8 mm wide pattern. We see that the effect of the indium bonded central portion was a higher surface temperature, resulting in a decrease in cavity mode wavelength of 7 nm over a distance of 3 mm. In Figure 3, we plot the measured reflectivity spectra for x = 18, 19, 20 , 21 mm in Figure 2. We see that although the cavity mode shifts significantly here, the stop band of the reflectance stays nearly constant. In Figure 4 we show the cavity mode along one dir
{"title":"Periodically Induced Mode Shift In Vertical Cavity Fabry Perot Etalons Grown By Molecular Beam Epitaxy","authors":"L. Eng, K. Toh, C. Chang-Hasnain, K. Bacher, J. Harris","doi":"10.1109/LEOSST.1994.700553","DOIUrl":"https://doi.org/10.1109/LEOSST.1994.700553","url":null,"abstract":"Two dimensional multiple wavelength vertical cavity surface emitting laser (VCSEL) arrays are promising for ultrahigh capacity optical networks using wavelength division multiplexing (WDM). The emission wavelength of a VCSEL is determined by the laser cavity round trip phase condition, which can be varied across the array by varying the thickness of either the cavity or the dielectric mirror layers. In prior work, a 2D VCSEL array emitting 140 distinct wavelengths was reported [ 13 using a spatially tapered mirror layer in the VCSEL caused by the inherent beam flux gradient in a Molecluar Beam Epitaxy (MBE) system. In this work, we demonstrate an induced lateral variation in cavity thickness of a GaAs/AlAs Fabry Perot resonator. By indium bonding the substrate to patterned backing wafers we induce a lateral surface temperature gradient on the substrate, thereby altering the GaAs desorption rate across the wafer during the growth of the cavity. Above substrate temperatures of 640 C, the GaAs growth rate is a strongly decreasing function of temperature [2]. Previously, Goodhue et. al. achieved substrate surface temperature differences of 30 50 C by mounting the substrates, using indium, to molybdenum blocks machined with 1 mm deep grooves and a 10 mm period [3]. They observed a near 3 fold decrease in GaAs growth rate in the high temperature regions of the wafer. In our work we have used indium to selectively bond the GaAs substrate to GaAs wafers which have patterns ranging from 2 to 8 mm. The advantage of this technique is that we can define the patterns lithographically. We then grow passive Fabry Perot cavities consisting of AlAs/GaAs Bragg mirror stacks centered at 950 nm, 10.5 pairs on the bottom and 8 on the top, and a 300 nm thick GaAs cavity. The calculated cavity mode of this structure is 980 nm. Both mirrors are grown at a substrate temperature of 600 C and the cavity is grown at approximately 700 C. A schematic of this technique is shown in Figure 1. We expect the mirrors to be uniform since they are grown below the gallium desorption temperature. The cavity, however, will have a thickness variation across the wafer due to the induced surface temperature difference in a regime in which significant gallium desorption occurs. We characterize the material by measuring reflectivity spectra across the wafer, and mapping the Fabry Perot wavelength. The spatial resolution of the measurement is 100 pm. Figure 2 shows the measured cavity mode position perpendicular to the direction of a single 8 mm wide pattern. We see that the effect of the indium bonded central portion was a higher surface temperature, resulting in a decrease in cavity mode wavelength of 7 nm over a distance of 3 mm. In Figure 3, we plot the measured reflectivity spectra for x = 18, 19, 20 , 21 mm in Figure 2. We see that although the cavity mode shifts significantly here, the stop band of the reflectance stays nearly constant. In Figure 4 we show the cavity mode along one dir","PeriodicalId":379594,"journal":{"name":"Proceedings of IEE/LEOS Summer Topical Meetings: Integrated Optoelectronics","volume":"245 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131726365","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 : 1994-07-06DOI: 10.1109/LEOSST.1994.700505
G. Khoe, H. Boom, E. Put
{"title":"LAN Interconnection Based On A Cross-connected Multi-wavelength Layer","authors":"G. Khoe, H. Boom, E. Put","doi":"10.1109/LEOSST.1994.700505","DOIUrl":"https://doi.org/10.1109/LEOSST.1994.700505","url":null,"abstract":"","PeriodicalId":379594,"journal":{"name":"Proceedings of IEE/LEOS Summer Topical Meetings: Integrated Optoelectronics","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133711786","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 : 1994-07-06DOI: 10.1109/LEOSST.1994.700493
L. Berthelon, C. Coeurjolly, P. Perrier, O. Gautheron, A. Noury, V. Havard
{"title":"Experimental Implementation Of A Cellular High Capacity Photonic Transport Network","authors":"L. Berthelon, C. Coeurjolly, P. Perrier, O. Gautheron, A. Noury, V. Havard","doi":"10.1109/LEOSST.1994.700493","DOIUrl":"https://doi.org/10.1109/LEOSST.1994.700493","url":null,"abstract":"","PeriodicalId":379594,"journal":{"name":"Proceedings of IEE/LEOS Summer Topical Meetings: Integrated Optoelectronics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130938294","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 : 1994-07-06DOI: 10.1109/LEOSST.1994.700446
G. B. Thompson, G. Robinson, J. Scott, C. Mahon, F. Peters, B. Thibeault, L. Coldren
Asymmetric Fabry-Perot modulators (AFPMs) possess many qualities which make them excellent candidates for use in smart pixel applications [l]. They inherently operate in a surface normal configuration and are polarization independent. Devices have been designed to achieve low insertion loss, high contrast ratio, low voltage operation and high electrical bandwidth [2-31. Recently, we have extended this work in the direction of packaged arrays with low voltage (0-5V) and high bandwidth (10 GHz) operation. The design includes intracavity contacts for low series resistance and coplanar transmission lines on a semi-insulating substrate for impedance matching. The package includes standard microwave (SMA) connectors and a planar microlens array. The AFPM consists of a multiple quantum well (MQW) p-i-n diode between two DBR mirrors of unequal reflectivity which form a resonant cavity. In the zero-bias, low absorption state, the reflectivity is high (typically > 50%). Applying an electric field across the p-i-n diode increases the cavity absorption via the quantum confined Stark effect (QCSE), decreasing the effective back mirror reflectivity to match that of the front mirror and nulling out the reflected signal. The device design parameters include the front mirror reflectivity, the number of quantum wells, the quantum well and barrier thicknesses and compositions, thickness of the contact regions, operating voltage swing and the operating wavelength. Since the QCSE can be treated as an instantaneous process on picosecond time scales, the modulation speed is limited in practice only by the speed with which the field applied across the MQW region can be modulated. Quantum well material (1 OOA GaAs wells with 45A A10.3Ga0.7As barriers) was characterized in terms of absorption as a function of wavelength for different applied voltages (or equivalently, electric fields) using photocurrent measurements. Using this data, a modulator was designed to have €3 dB insertion loss and >lo GHz bandwidth (with a 50Q parallel termination resistor) for a 4V modulation swing and operate at a wavelength of about 853 nm to be compatible with GaAs QW laser sources. Typical DC characteristics are shown in Figure 1. Growth non-uniformity across the array adversely affects performance. We fabricated a I x 18 array of AFPMs with a 250 pm pitch. We observed approximately a 1 nm variation in the optimum wavelength of operation across the array. This translates into a maximum insertion loss of 4 dB and minimum contrast ratio of 8 dB across the entire array for a fixed wavelength of operation. Location and orientation of an array on the wafer in addition to the optical bandwidth of the device determine these values and so improvements are possible i n the future. Microwave measurements were performed using an HP85 1 OC network analyzer. The transmission line and device were characterized by measuring S i 1 at a bias of 2V. The equivalent circuit model is shown in the inset of Figur
{"title":"1 X 18 Array Of Low Voltage, Asymmetric Fabry-Perot Modulators For Gigabit Data Transmission Applications","authors":"G. B. Thompson, G. Robinson, J. Scott, C. Mahon, F. Peters, B. Thibeault, L. Coldren","doi":"10.1109/LEOSST.1994.700446","DOIUrl":"https://doi.org/10.1109/LEOSST.1994.700446","url":null,"abstract":"Asymmetric Fabry-Perot modulators (AFPMs) possess many qualities which make them excellent candidates for use in smart pixel applications [l]. They inherently operate in a surface normal configuration and are polarization independent. Devices have been designed to achieve low insertion loss, high contrast ratio, low voltage operation and high electrical bandwidth [2-31. Recently, we have extended this work in the direction of packaged arrays with low voltage (0-5V) and high bandwidth (10 GHz) operation. The design includes intracavity contacts for low series resistance and coplanar transmission lines on a semi-insulating substrate for impedance matching. The package includes standard microwave (SMA) connectors and a planar microlens array. The AFPM consists of a multiple quantum well (MQW) p-i-n diode between two DBR mirrors of unequal reflectivity which form a resonant cavity. In the zero-bias, low absorption state, the reflectivity is high (typically > 50%). Applying an electric field across the p-i-n diode increases the cavity absorption via the quantum confined Stark effect (QCSE), decreasing the effective back mirror reflectivity to match that of the front mirror and nulling out the reflected signal. The device design parameters include the front mirror reflectivity, the number of quantum wells, the quantum well and barrier thicknesses and compositions, thickness of the contact regions, operating voltage swing and the operating wavelength. Since the QCSE can be treated as an instantaneous process on picosecond time scales, the modulation speed is limited in practice only by the speed with which the field applied across the MQW region can be modulated. Quantum well material (1 OOA GaAs wells with 45A A10.3Ga0.7As barriers) was characterized in terms of absorption as a function of wavelength for different applied voltages (or equivalently, electric fields) using photocurrent measurements. Using this data, a modulator was designed to have €3 dB insertion loss and >lo GHz bandwidth (with a 50Q parallel termination resistor) for a 4V modulation swing and operate at a wavelength of about 853 nm to be compatible with GaAs QW laser sources. Typical DC characteristics are shown in Figure 1. Growth non-uniformity across the array adversely affects performance. We fabricated a I x 18 array of AFPMs with a 250 pm pitch. We observed approximately a 1 nm variation in the optimum wavelength of operation across the array. This translates into a maximum insertion loss of 4 dB and minimum contrast ratio of 8 dB across the entire array for a fixed wavelength of operation. Location and orientation of an array on the wafer in addition to the optical bandwidth of the device determine these values and so improvements are possible i n the future. Microwave measurements were performed using an HP85 1 OC network analyzer. The transmission line and device were characterized by measuring S i 1 at a bias of 2V. The equivalent circuit model is shown in the inset of Figur","PeriodicalId":379594,"journal":{"name":"Proceedings of IEE/LEOS Summer Topical Meetings: Integrated Optoelectronics","volume":"316 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131611787","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 : 1994-07-06DOI: 10.1109/LEOSST.1994.700461
I. Ogura, M. Kajita, S. Kawai, K. Kasahara
Two-dimensionally integrated multiple wavelength arrays using VCSELs or VCSEL-based optical functional device arrays such as V S W s are expected to provide a wider-bandwidth and improved functionality, such as wavelength addressing.') A multiple wavelength VCSEL array, grown with a specific thickness grading, can provide fixed wavelength separation.2) To fully utilize the advantages of the multiple wavelength scheme, a more flexible fabrication technique is needed for providing the arrays with the desired wavelength separation or distribution, such as periodic distribution.
{"title":"Fabrication Of Multiple Wavelength Vertical-cavity Surface-emitting Laser Array Using Flip-chip Bonding","authors":"I. Ogura, M. Kajita, S. Kawai, K. Kasahara","doi":"10.1109/LEOSST.1994.700461","DOIUrl":"https://doi.org/10.1109/LEOSST.1994.700461","url":null,"abstract":"Two-dimensionally integrated multiple wavelength arrays using VCSELs or VCSEL-based optical functional device arrays such as V S W s are expected to provide a wider-bandwidth and improved functionality, such as wavelength addressing.') A multiple wavelength VCSEL array, grown with a specific thickness grading, can provide fixed wavelength separation.2) To fully utilize the advantages of the multiple wavelength scheme, a more flexible fabrication technique is needed for providing the arrays with the desired wavelength separation or distribution, such as periodic distribution.","PeriodicalId":379594,"journal":{"name":"Proceedings of IEE/LEOS Summer Topical Meetings: Integrated Optoelectronics","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130986664","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 : 1994-07-06DOI: 10.1109/LEOSST.1994.700548
L. Kolodziejski
Substantial progress in recent years by the solid source molecular beam epitaxy (MBE) community has demonstrated the feasibility of the (Zn,Mg)(S,Se) material system for realizing laser diodes operating in the green to blue spectral region. For the Zn-chalcogenide quaternary, all of the constituent elements have very high vapor pressures, and require the regulation of thermal effusion ovens operating at low temperatures (-100-300"C), thus creating a difficulty in reproducibility of the 11-VI alloy composition and emission wavelength. Gaseous source epitaxy technologies [metalorganic (MOMBE) and gas source molecular beam epitaxy (GSMBE)] address these difficulties by employing mass flow controllers to regulate the flux of hydride and metalorganic gas sources. The ultrahigh vacuum environment of MOMBWGSMBE enables implementation of a nitrogen plasma source, which is necessary for p-type doping by the incorporation of nitrogen acceptors into the 11-VI material system. In this paper, the application of the gaseous source epitaxial growth approaches to the fabrication of wide bandgap 11-VI materials and heterostructures will be summarized. In addition, the use of photo-assisted epitaxy, which enables in situ modification of surface chemical reactions, has provided a significant growth rate enhancement, as well as a growth rate retardation, and is dependent on the species present at the growth front. (An electron beam incident to the surface has also been found to simulate the photo-assisted epitaxy effect by creating a significant growth rate enhancement.) To expand the range of lattice constants available for the heteroepitaxy of ZnSe-based heterostructures, the epitaxial growth of ZnSe onto novel 111-V epitaxial layers containing (In,Ga)P is also under intense investigation; the initial characterization of this new IIVyIII-V heterostructure will be described. Utilizing gas source molecular beam epitaxy, ZnSe has been grown using a hydride compound for the source of the high vapor pressure anion species. Nand p-type doping has been investigated using a nitrogen plasma cell for acceptor species of nitrogen and a solid ZnC12 source for donor species of chlorine, respectively. The use of hydride compounds, however, raises the issue of hydrogen incorporation and the possibility that hydrogen may electrically passivate donors or acceptors. High quality ZnSe:Cl has been grown with atomic c1 concentrations approaching lo2' as indicated by secondary ion mass spectrometry (SIMS). At incorporation levels greater than lo2' ~ m ~ , an appreciable decrease in the growth rate has been observed. The sharp transition to a negligible growth rate is atmbuted to the Occurrence of a surface chemical reaction originating from C1 and H which are present in the GSMBE environment. For C1 concentrations as high as 4 ~ 1 0 ' ~ the films exhibited high crystalline quality, as indicated by photoluminescence originating from a single intense donor-bound excitonic transition. In
近年来固体源分子束外延(MBE)领域取得的重大进展证明了(Zn,Mg)(S,Se)材料体系实现绿色到蓝色光谱区域激光二极管工作的可行性。对于硫族锌四元化合物，所有组成元素都具有非常高的蒸汽压，并且需要在低温(-100-300”C)下调节热渗出炉，从而造成11-VI合金成分和发射波长的重现性困难。气体源外延技术[金属有机(MOMBE)和气体源分子束外延(GSMBE)]通过使用质量流量控制器来调节氢化物和金属有机气体源的通量来解决这些困难。MOMBWGSMBE的超高真空环境可以实现氮等离子体源，这是将氮受体掺入11-VI材料体系中进行p型掺杂所必需的。本文综述了气源外延生长方法在制备宽禁带11-VI材料和异质结构中的应用。此外，光辅助外延的使用，使表面化学反应的原位修饰，提供了一个显着的生长速度提高，以及生长速度减慢，这取决于存在于生长前沿的物种。(入射到表面的电子束也被发现通过产生显著的生长速率增强来模拟光辅助外延效应。)为了扩大ZnSe基异质结构外延的晶格常数范围，ZnSe在含有(In,Ga)P的新型111-V外延层上的外延生长也得到了深入的研究;本文将描述这种新的iivii - ii - v异质结构的初步表征。利用气源分子束外延，利用氢化物化合物作为高蒸汽压阴离子源生长ZnSe。采用氮质浆电池和固体ZnC12源分别对氮的受体和氯的供体进行了Nand p型掺杂研究。然而，氢化物的使用引发了氢掺入的问题，以及氢可能电钝化供体或受体的可能性。二级离子质谱(SIMS)表明，高质量的ZnSe:Cl在c1原子浓度接近lo2'的情况下生长。当掺入量大于2′~ m ~时，观察到生长速率明显下降。由于GSMBE环境中存在由C1和H引起的表面化学反应的发生，生长速率急剧转变为可忽略不计。当C1浓度高达4 ~ 10′~时，薄膜表现出较高的晶体质量，这表明由单一强烈的供体结合激子跃迁引起的光致发光。在ZnSe:Cl的情况下，H存在于ZnSe层中，但似乎没有对n型薄膜的电学性能产生不利影响。利用电容-电压(C-V)谱图和霍尔效应测量对ZnSe:Cl层进行电学表征，得到的电子浓度值与SIMS得到的电子浓度值较为接近。氮掺杂p型ZnSe中氢的掺入有明显的差异
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