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Title: Room temperature continuous-wave operation of GaInNAs long wavelength VCSELs

Abstract

Vertical cavity surface-emitting lasers (VCSELs) are becoming increasingly important for short-haul optical fiber transmission systems. Given the commercial success of GaAs-based 850nm VCSELs, dramatic enhancements in transmission bandwidth and distance can be achieved in conventional single- and multi-mode fiber by extending the emission wavelength to the 1300nm-1550nm range. GaInNAs is a promising active layer material grown on GaAs that can achieve 1300nm emission [l], and electrically pulsed broad-area GaInNAs VCSELs [2,3] have been realized. Here we take advantage of the properties of GaAs-based materials-thermally-conductive high contrast mirrors and AlAs-oxide current apertures-to demonstrate for the first time low-threshold ({approx}1 mA) GaInNAs VCSELs emitting at a wavelength of 1200 nm under continuous-wave room temperature operation. The device structure is shown schematically in figure 1. The bottom mirror consists of a 22.5-period n-doped GaAs/AlAs distributed Bragg reflector (DBR) designed for a center wavelength {lambda} near 1200nm, the top mirror is a 22-period p-doped DBR whose reflectance is enhanced by a Ti/Au contact electrode, and the GaAs {lambda} cavity contains three 70{angstrom}, Ga{sub 0.3}In{sub 0.7}N{sub 0.02}As{sub 0.98} quantum wells (QWs) separated by 200{angstrom} GaAs barriers. The epilayers were grown by molecular beam epitaxy using solid-source arsenic and a rf nitrogen plasma source. After growth,more » the first 17 mirror periods of the top mirror were dry etched and subsequently capped with SiO{sub 2}, and the remaining three periods were etched to expose the AlAs for lateral oxidation, which formed square unoxidized apertures as small as 3.6 {micro}m on a side. After the top contact metalization, devices were mounted without heat sinking on a glass slide for optical emission through the substrate, which was contacted electrically with indium solder. The output power and voltage vs. injection current for a 5{micro}m x 5{micro}m device operating CW at room temperature is shown in figure 2. The threshold current is approximately 1.3 mA, and the slope efficiency is 0.045 W/A. CW operation was possible in spite of an extremely high threshold voltage of 10.3 V which resulted from unoptimized doping and composition profiles at the heterointerfaces of the p-DBR. This created a large degree of self heating which limited the maximum output power to 0.080 mW at 3.8 mA. Figure 3 shows emission spectra at threshold, with a lasing wavelength of 1201.54 nm, and at 2.6 times threshold. The device lased in a single transverse and longitudinal mode, and far above threshold, the side mode suppression1 ratio was in excess of 40 dB. As seen in figure 4, the wavelength shifted with dissipated power at a rate of 0.0924 nm/mW. Given a wavelength shift with temperature of 0.0743 n d K obtained from broad area VCSELs [4], this indicates a calculated temperature rise of {approx}60K above the ambient at peak output power and a thermal impedance of 1.24 WmW. CW laser operation also occurred for device sizes ranging from 3.6 {micro}m to 6.4 {micro}m, with threshold currents from 0.94 to 2.3 mA and slope efficiency as high as 0.049 W/A. In summary, we have demonstrated low-threshold GaInNAs VCSELs operating continuous-wave at room temperature, with an emission wavelength of 1200 nm. Higher output power will be possible by reducing the resistance of the p-DBR, and 1300 nm emission should be achieved by increasing the indium and/or nitrogen content of the GaInNAs/GaAs multiple quantum well active layer.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab., CA (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
15006371
Report Number(s):
UCRL-JC-137689
TRN: US200409%%53
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: 58th Annual Device Research Conference, Denver, CO (US), 06/19/2000--06/21/2000; Other Information: PBD: 22 Jun 2000
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 42 ENGINEERING; A CENTERS; APERTURES; EFFICIENCY; EMISSION SPECTRA; FIBERS; HEATING; IMPEDANCE; INDIUM; LASERS; MOLECULAR BEAM EPITAXY; NITROGEN; OPTICAL FIBERS; OXIDATION; THRESHOLD CURRENT; WAVELENGTHS

Citation Formats

Larson, M C, Coldren, C W, Spruytte, S G, Peterson, H E, and Harris, J S. Room temperature continuous-wave operation of GaInNAs long wavelength VCSELs. United States: N. p., 2000. Web. doi:10.1109/DRC.2000.877113.
Larson, M C, Coldren, C W, Spruytte, S G, Peterson, H E, & Harris, J S. Room temperature continuous-wave operation of GaInNAs long wavelength VCSELs. United States. doi:10.1109/DRC.2000.877113.
Larson, M C, Coldren, C W, Spruytte, S G, Peterson, H E, and Harris, J S. Thu . "Room temperature continuous-wave operation of GaInNAs long wavelength VCSELs". United States. doi:10.1109/DRC.2000.877113. https://www.osti.gov/servlets/purl/15006371.
@article{osti_15006371,
title = {Room temperature continuous-wave operation of GaInNAs long wavelength VCSELs},
author = {Larson, M C and Coldren, C W and Spruytte, S G and Peterson, H E and Harris, J S},
abstractNote = {Vertical cavity surface-emitting lasers (VCSELs) are becoming increasingly important for short-haul optical fiber transmission systems. Given the commercial success of GaAs-based 850nm VCSELs, dramatic enhancements in transmission bandwidth and distance can be achieved in conventional single- and multi-mode fiber by extending the emission wavelength to the 1300nm-1550nm range. GaInNAs is a promising active layer material grown on GaAs that can achieve 1300nm emission [l], and electrically pulsed broad-area GaInNAs VCSELs [2,3] have been realized. Here we take advantage of the properties of GaAs-based materials-thermally-conductive high contrast mirrors and AlAs-oxide current apertures-to demonstrate for the first time low-threshold ({approx}1 mA) GaInNAs VCSELs emitting at a wavelength of 1200 nm under continuous-wave room temperature operation. The device structure is shown schematically in figure 1. The bottom mirror consists of a 22.5-period n-doped GaAs/AlAs distributed Bragg reflector (DBR) designed for a center wavelength {lambda} near 1200nm, the top mirror is a 22-period p-doped DBR whose reflectance is enhanced by a Ti/Au contact electrode, and the GaAs {lambda} cavity contains three 70{angstrom}, Ga{sub 0.3}In{sub 0.7}N{sub 0.02}As{sub 0.98} quantum wells (QWs) separated by 200{angstrom} GaAs barriers. The epilayers were grown by molecular beam epitaxy using solid-source arsenic and a rf nitrogen plasma source. After growth, the first 17 mirror periods of the top mirror were dry etched and subsequently capped with SiO{sub 2}, and the remaining three periods were etched to expose the AlAs for lateral oxidation, which formed square unoxidized apertures as small as 3.6 {micro}m on a side. After the top contact metalization, devices were mounted without heat sinking on a glass slide for optical emission through the substrate, which was contacted electrically with indium solder. The output power and voltage vs. injection current for a 5{micro}m x 5{micro}m device operating CW at room temperature is shown in figure 2. The threshold current is approximately 1.3 mA, and the slope efficiency is 0.045 W/A. CW operation was possible in spite of an extremely high threshold voltage of 10.3 V which resulted from unoptimized doping and composition profiles at the heterointerfaces of the p-DBR. This created a large degree of self heating which limited the maximum output power to 0.080 mW at 3.8 mA. Figure 3 shows emission spectra at threshold, with a lasing wavelength of 1201.54 nm, and at 2.6 times threshold. The device lased in a single transverse and longitudinal mode, and far above threshold, the side mode suppression1 ratio was in excess of 40 dB. As seen in figure 4, the wavelength shifted with dissipated power at a rate of 0.0924 nm/mW. Given a wavelength shift with temperature of 0.0743 n d K obtained from broad area VCSELs [4], this indicates a calculated temperature rise of {approx}60K above the ambient at peak output power and a thermal impedance of 1.24 WmW. CW laser operation also occurred for device sizes ranging from 3.6 {micro}m to 6.4 {micro}m, with threshold currents from 0.94 to 2.3 mA and slope efficiency as high as 0.049 W/A. In summary, we have demonstrated low-threshold GaInNAs VCSELs operating continuous-wave at room temperature, with an emission wavelength of 1200 nm. Higher output power will be possible by reducing the resistance of the p-DBR, and 1300 nm emission should be achieved by increasing the indium and/or nitrogen content of the GaInNAs/GaAs multiple quantum well active layer.},
doi = {10.1109/DRC.2000.877113},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2000},
month = {6}
}

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