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i l St. Petersburg Polytechnic University Journal. Physics and Mathematics. 2022 Vol. 15, No. 3.3 Научно-технические ведомости СПбГПУ. Физико-математические науки. 15 (3.3) 2022
Conference materials UDC 535.015
DOI: https://doi.org/10.18721/JPM.153.332
The investigation of optical coupling of microlasers with tapered fiber
N. A. Fominykh E. I. Moiseev \ I. S. Makhov \ K. N. Min'kov 3, A. M. Nadtochiy 1 4, Yu. A. Guseva 4, M. M. Kulagina 4, S. A. Mintairov 4, N. A. Kalyuzhnyy 4, N. V. Kryzhanovskaya ,2, A. E. Zhukov 1
1 HSE University, St. Petersburg, Russia;
2 Alferov University, St. Petersburg, Russia;
3 Russian Quantum Center, Moscow, Russia;
4 Ioffe Institute, St. Petersburg, Russia H [email protected] Abstract. We present an investigation of optical coupling of injection microdisk and microring lasers with different diameters with a tapered fiber. We studied the dependences of the laser dominant mode intensity on the distance between the tapered fiber and the microlaser's sidewall. For every studied laser a sharp intensity growth by 2—3 orders of magnitude was observed when the tapered fiber came in contact with the microlaser. We compared lasing spectra received by the tapered fiber and by the microobjective. Though the intensity of the electroluminescence signal received by the tapered fiber was lower than that coupled by the microobjective, the ratio of the dominant (lasing) mode intensity to spontaneous emission was noticeably higher for the case of the tapered fiber.
Keywords: quantum well-dots, microlasers, microdisk resonators, tapered fiber, whispering gallery modes
Funding: The fabrication of the lasers was supported by Russian Foundation for Basic Research, project № 20-02-00334. The study of the output power was implemented in the framework of the Basic Research Program at the National Research University Higher School of Economics (HSE University). The studies of laser's spectral characteristics were supported by the Ministry of Science and Higher Education of the Russian Federation, project № 07912020-0002.
Citation: Fominykh N. A., Moiseev E. I., Makhov I. S., Min'kov K. N., Nadtochiy A. M., Guseva Yu. A., Kulagina M. M., Mintairov S. A., Kalyuzhnyy N. A., Kryzhanovskaya N. V., Zhukov A. E., The investigation of optical coupling of microlasers with tapered fiber. St. Petersburg State Polytechnical University Journal. Physics and Mathematics, 15 (3.3) (2022) 167-170. DOI: https://doi.org/10.18721/JPM.153.332
This is an open access article under the CC BY-NC 4.0 license (https://creativecommons. org/licenses/by-nc/4.0/)
Материалы конференции УДК 535.015
DOI: https://doi.org/10.18721/JPM.153.332
Исследование оптической связи микролазеров с утоненным волокном
Н. А. Фоминых ,'2И, Э. И. Моисеев ,, И. С. Махов ,, К. Н. Миньков 3, А. М. Надточий м, Ю. А. Гусева 4, М. М. Кулагина 4, С. А. Минтаиров 4, Н. А. Калюжный 4, Н. В. Крыжановская ,2, А. Е. Жуков 1
1 Национальный исследовательский университет «Высшая школа экономики», Санкт-Петербург, Россия; 2 Алфёровский университет, Санкт-Петербург, Россия;
© Fominykh N. A., Moiseev E. I., Makhov I. S., Min'kov K. N., Nadtochiy A. M., Guseva Yu. A., Kulagina M. M., Mintairov S. A., Kalyuzhnyy N. A., Kryzhanovskaya N. V., Zhukov A. E., 2022. Published by Peter the Great St.Petersburg Polytechnic University.
3 Российский квантовый центр, Москва, Россия;
4 Физико-технический институт им. А. Ф. Иоффе, Санкт-Петербург, Россия н [email protected]
Аннотация. В данной работе представлено исследование оптической связи инжекционных микродисковых и микрокольцевых лазеров различного диаметра с утоненным оптическим волокном. Были исследованы зависимости интенсивности доминирующей моды лазера от расстояния между утоненным волокном и боковой стенкой микролазера. Для каждого исследованного лазера наблюдался резкий рост интенсивности на 2—3 порядка при контакте волокна с микролазером. Проведено сравнение спектров лазерной генерации, полученных через утоненное волокно и микрообьектив. Интенсивность сигнала электролюминесценции в случае утоненного волокна была меньше, чем у сигнала с микрообъектива, но отношение интенсивности доминирующей лазерной моды к спонтанному излучению для утоненного волокна заметно выше.
Ключевые слова: квантовые яма-точки, микролазеры, микродисковый резонатор, утоненное волокно, моды шепчущей галереи
Финансирование: Изготовление лазеров было поддержано Российским фондом фундаментальных исследований, проект № 20-02-00334. Исследование выходной мощности выполнено в рамках программы фундаментальных исследований НИУ ВШЭ (Университет ВШЭ). Исследование спектральных характеристик лазеров было поддержано Министерством науки и высшего образования РФ, проект № 0791-20200002.
Ссылка при цитировании: Фоминых Н. А., Моисеев Э. И., Махов И. С., Миньков К. Н., Надточий А. М., Гусева Ю. А., Кулагина М. М., Минтаиров С. А., Калюжный Н. А., Крыжановская Н. В., Жуков А. Е., Исследование оптической связи микролазеров с утоненным волокном // Научно-технические ведомости СПбГПУ. Физико-математические науки. 2022. Т. 15. № 3.3. C. 167-170. DOI: https://doi.org/10.18721/ JPM.153.332
Статья открытого доступа, распространяемая по лицензии CC BY-NC 4.0 (https:// creativecommons.org/licenses/by-nc/4.0/)
Introduction
In recent years, the investigation of semiconductor microdisk (MD) and microring (MR) lasers draws a lot of attention because microlasers of this design can be used as building blocks in future microphotonic and nanophotonic devices [1]. MD and MR lasers support whispering gallery modes (WGM) with high quality factor and, accordingly, low output losses [2]. WGM microlasers are promising candidates for optically coupled systems due to lateral light output. Coupling of microlaser emission by tapered fiber has already been investigated for the cases of passive WGM microresonators [3] and WGM microlasers with optical pumping [4]. In this work we study the optical coupling of injection semiconductor MD and MR lasers with different diameters (15-50 ^m) with tapered fiber.
Materials and Methods
The studied injection microlasers were fabricated from a laser epitaxial heterostructure synthesized on a n+-GaAs substrate by MOCVD with an active region representing a 5-layer array of InGaAs/GaAs quantum well-dots. MD and MR lasers a height of about 5 ^m and diameters varied in range from 15 ^m to 50 ^m were formed by photolithography and dry etching. We used AgMn/Ni/Au metallization to form ring contacts to the p+-GaAs layer at the tops of the mesas. The GaAs substrate was thinned to approximately 100 ^m, and a solid electrical AuGe/Ni/Au n-contact was fabricated on its reverse surface.
Horizontal and vertical visualization was achieved by Mitutoyo M Plan Apo NIR 20x objective and CCD camera. Electroluminescence (EL) of MD and MR lasers was excited by a stabilized
© Фоминых Н. А., Моисеев Э. И., Махов И. С., Миньков К. Н., Надточий А. М., Гусева Ю. А., Кулагина М. М., Минтаиров С. А., Калюжный Н. А., Крыжановская Н. В., Жуков А. Е., 2022. Издатель: Санкт-Петербургский политехнический университет Петра Великого.
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Physical optics
DC current with a Keithley 2400 Series SourceMeter® power supply. The EL spectra were analysed with a Yokogawa AQ6370C optical spectrum analyser.
The tapered fiber was fabricated by adiabatic stretching method which allows setting a shape and parameters of the tapered section [5]. In this work we used the fiber with 2 ^m diameter of the thinnest part. The tapered fiber was cleaved in the thinned part. To achieve more careful positioning near microlaser we mounted the fiber on a 3-dimentional translation stage. The coupling scheme is represented in Fig. 1.
Fig. 1. The coupling scheme
Results and Discussion
We located the tapered fiber near the active region of the structures as shown in figure 1 to study the dependencies of the dominant mode intensity on the distance between the tapered fiber and the microlaser's side wall (X). We observed a sharp intensity growth by 2—3 orders of magnitude when the tapered fiber came in contact with the microlaser (Fig. 2). Any changes of the resonant line full width at half maximum were not found at the contact of the microlaser with fiber probably due to the low spectral resolution of the optical spectrum analyser used.
To receive lasing spectra by the tapered fiber we located it in contact with the sidewall (X = 0) of the studied microlasers and opposite their active region (Fig. 1). Such careful positioning allowed us to obtain lasing spectra with maximum intensity (Fig. 2). The lasing spectra above the threshold of the MD laser with 40 ^m diameter received by the tapered fiber and by the microobjective are shown in Fig. 3. Despite lower intensity of the spectra received by the tapered fiber in comparison with that received by the microobjective the ratio of the dominant mode intensity to spontaneous emission was noticeably higher in the case of the fiber. The coupling of the lasing mode to the tapered fiber can be the reason of the higher resonant mode intensity. We also studied the evolution of the emission spectra received by the tapered fiber and by the microobjective with increasing injection current to determine a threshold current. There were no differences in the threshold currents determined by the two methods.
14 28
42
56
70
X, |im
Fig. 2. The dependence of the dominant mode intensity on the distance between the tapered fiber and the 20 ^m MR laser
1080 1090 Wavelength, nm
Fig. 3. EL spectra of 40 ^m MD laser at 10 mA current received by the tapered fiber and by the microobjective
Conclusion
The outcoupling of the lasing emission from an injection MD and MR lasers into a tapered fiber without the evidence of the lasing parameters deterioration was realized for the first time. A sharp intensity growth by 2—3 orders of magnitude was observed when the tapered fiber came in
contact with the microlaser. In comparison with the spectra received by the microobjective the ratio of the dominant lasing mode intensity to spontaneous emission was noticeably higher for the case of the tapered fiber.
Acknowledgments
The tapered fiber was fabricated using the equipment of the Center for Collective Use VNIIOFI (ckp.vniiofi.ru).
REFERENCES
1. Schmidt C., Chipouline A., Kasebier T., Kley E.-B., Tunnermann A., Pertsch T., Shuvayev V., Deych L. I., Observation of optical coupling in microdisk resonators, Physical Review A. 80 (4) (2009) 043841.
2. Kryzhanovskaya N. V. et al., Evaluation of energy-to-data ratio of quantum-dot microdisk lasers under direct modulation, Journal of Applied Physics. 126 (6) (2019) 063107.
3. Srinivasan K., Painter O., Mode coupling and cavity-quantum-dot interactions in a fiber-coupled microdisk cavity, Physical Review A. 75 (2) (2007) 023814.
4. Cai M., Painter O., Vahala K. J., Sercel P. C., Fiber-coupled microsphere laser, Optics letters. 25 (19) (2000) 1430-1432.
5. Ivanov A. D., Min'kov K. N., Samoilenko A. A., Method of producing tapered optical fiber, Journal of Optical Technology. 84 (7) (2017) 500-503.
THE AUTHORS
FOMINYKH Nikita A.
[email protected] ORCID: 0000-0003-3919-6410
KULAGINA Marina M.
[email protected] ORCID: 0000-0002-8721-185X
MOISEEV Eduard I.
ORCID: 0000-0003-3686-935X
MINTAIROV Sergey A.
[email protected] ORCID: 0000-0002-6176-6291
MAKHOV Ivan S. [email protected]
ORCID: 0000-0003-4527-1958
KALYUZHNYY Nikolay A.
[email protected] ORCID: 0000-0001-8443-4663
MIN'KOV Kirill N.
[email protected] ORCID: 0000-0002-6462-2453
KRYZHANOVSKAYA Natalia V.
[email protected] ORCID: 0000-0002-4945-9803
NADTOCHIY Alexey M. [email protected] ORCID: 0000-0003-0982-907X
ZHUKOV Alexey E.
[email protected] ORCID: 0000-0002-4579-0718
GUSEVA Yulia A.
[email protected] ORCID: 0000-0002-7035-482X
Received 13.07.2022. Approved after reviewing 14.07.2022. Accepted 29.07.2022.
© Peter the Great St. Petersburg Polytechnic University, 2022
