Improving P-Doped DBRs Operation at Cryogenic Temperatures: Investigating Different Mirror Geometry
The use of vertical-cavity-surface-emitting lasers with ability to operate at cryogenic temperatures (Cryo-VCSELs) is a promising path to implement optical data links between superconducting processors maintained in cryogenic environments (4 K range) and room temperature (RT) computing hardware. In...
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2024-01-01
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| author | Behzad Namvar Topi Uusitalo Heikki Virtanen Mircea Guina Jukka Viheriala |
| author_facet | Behzad Namvar Topi Uusitalo Heikki Virtanen Mircea Guina Jukka Viheriala |
| author_sort | Behzad Namvar |
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| description | The use of vertical-cavity-surface-emitting lasers with ability to operate at cryogenic temperatures (Cryo-VCSELs) is a promising path to implement optical data links between superconducting processors maintained in cryogenic environments (4 K range) and room temperature (RT) computing hardware. In order to achieve energy-efficient operation of a cryo-VCSEL, whether by passing current through the mirrors or utilizing intra-cavity contacts, a critical bottleneck for improving the operation is related to the p-doped distribute Bragg Reflectors (DBRs). This is because holes exhibit lower mobility and lower thermal conductivity compared to their n-side counterparts. To determine the actual temperature of an operating p-doped DBR and its impact on the behavior of the DBRs and the cryo-VCSEL, a thermal simulation using the finite-element method was conducted and validated with experimental results. Furthermore, we explored different mirror geometries to optimize both current flow and the growth complexity of the DBR. DBR layers with various interface shapes, such as uni-parabolic grading and three to five steps with different Al mole fractions, have been investigated. As a result of the study, we achieved more efficient operation at cryogenic temperatures, with a 60% reduction of the series resistance and a 39% reduction of the voltage penalty related to the p-doped DBR. |
| format | Article |
| id | doaj-art-322f34ebd4cf4162b285df87e60ab605 |
| institution | Kabale University |
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| language | English |
| publishDate | 2024-01-01 |
| publisher | IEEE |
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| series | IEEE Photonics Journal |
| spelling | doaj-art-322f34ebd4cf4162b285df87e60ab6052025-01-24T00:00:39ZengIEEEIEEE Photonics Journal1943-06552024-01-011641910.1109/JPHOT.2024.340250110551442Improving P-Doped DBRs Operation at Cryogenic Temperatures: Investigating Different Mirror GeometryBehzad Namvar0https://orcid.org/0000-0002-6849-5826Topi Uusitalo1https://orcid.org/0000-0002-7953-1036Heikki Virtanen2https://orcid.org/0000-0001-8978-6633Mircea Guina3https://orcid.org/0000-0002-9317-8187Jukka Viheriala4https://orcid.org/0000-0002-1483-5733Optoelectronics Research Center, Faculty of Engineering and Natural Science, Physics Unit / Photonics, Tampere University, Tampere, FinlandOptoelectronics Research Center, Faculty of Engineering and Natural Science, Physics Unit / Photonics, Tampere University, Tampere, FinlandOptoelectronics Research Center, Faculty of Engineering and Natural Science, Physics Unit / Photonics, Tampere University, Tampere, FinlandOptoelectronics Research Center, Faculty of Engineering and Natural Science, Physics Unit / Photonics, Tampere University, Tampere, FinlandOptoelectronics Research Center, Faculty of Engineering and Natural Science, Physics Unit / Photonics, Tampere University, Tampere, FinlandThe use of vertical-cavity-surface-emitting lasers with ability to operate at cryogenic temperatures (Cryo-VCSELs) is a promising path to implement optical data links between superconducting processors maintained in cryogenic environments (4 K range) and room temperature (RT) computing hardware. In order to achieve energy-efficient operation of a cryo-VCSEL, whether by passing current through the mirrors or utilizing intra-cavity contacts, a critical bottleneck for improving the operation is related to the p-doped distribute Bragg Reflectors (DBRs). This is because holes exhibit lower mobility and lower thermal conductivity compared to their n-side counterparts. To determine the actual temperature of an operating p-doped DBR and its impact on the behavior of the DBRs and the cryo-VCSEL, a thermal simulation using the finite-element method was conducted and validated with experimental results. Furthermore, we explored different mirror geometries to optimize both current flow and the growth complexity of the DBR. DBR layers with various interface shapes, such as uni-parabolic grading and three to five steps with different Al mole fractions, have been investigated. As a result of the study, we achieved more efficient operation at cryogenic temperatures, with a 60% reduction of the series resistance and a 39% reduction of the voltage penalty related to the p-doped DBR.https://ieeexplore.ieee.org/document/10551442/Cryogenic photonicsDBRsdistributed bragg reflectorsmirror gradingp-dopedsimulation |
| spellingShingle | Behzad Namvar Topi Uusitalo Heikki Virtanen Mircea Guina Jukka Viheriala Improving P-Doped DBRs Operation at Cryogenic Temperatures: Investigating Different Mirror Geometry IEEE Photonics Journal Cryogenic photonics DBRs distributed bragg reflectors mirror grading p-doped simulation |
| title | Improving P-Doped DBRs Operation at Cryogenic Temperatures: Investigating Different Mirror Geometry |
| title_full | Improving P-Doped DBRs Operation at Cryogenic Temperatures: Investigating Different Mirror Geometry |
| title_fullStr | Improving P-Doped DBRs Operation at Cryogenic Temperatures: Investigating Different Mirror Geometry |
| title_full_unstemmed | Improving P-Doped DBRs Operation at Cryogenic Temperatures: Investigating Different Mirror Geometry |
| title_short | Improving P-Doped DBRs Operation at Cryogenic Temperatures: Investigating Different Mirror Geometry |
| title_sort | improving p doped dbrs operation at cryogenic temperatures investigating different mirror geometry |
| topic | Cryogenic photonics DBRs distributed bragg reflectors mirror grading p-doped simulation |
| url | https://ieeexplore.ieee.org/document/10551442/ |
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