Mr. Andrei P. Bakoz Profile

Andrei P. Bakoz

Doctoral Candidate at Tyndall National Institute

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Publications (5)

Proceedings Article | 14 March 2023 Presentation + Paper

Laser Doppler vibrometry sensors implemented in a silicon photonic integrated circuit for measuring cardiovascular signals on bare skin

Yanlu Li, Soren Aasmul, Andrei Bakoz, Chirag Murendranath Patil, Padraic Morrissey, Tracy Wotherspoon, Owen Pullin, Felix Campano Casado, Petr Záruba, Roel Baets

Proceedings Volume 12355, 1235507 (2023) https://doi.org/10.1117/12.2648832

KEYWORDS: Laser Doppler velocimetry, Skin, Reflection, Signal to noise ratio, Doppler effect, Sensors, Tissue optics, Silicon photonics, Signal detection, Vibrometry

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Proceedings Article | 1 April 2020 Presentation + Paper

Relaxation oscillations suppression and undamping in a hybrid photonic crystal laser

Anton Kovalev, Sharon Butler, Andrei Bakoz, Stephen Hegarty, Liam O’Faolain, Evgeny Viktorov

Proceedings Volume 11356, 113560P (2020) https://doi.org/10.1117/12.2556531

KEYWORDS: Photonic crystals, Semiconductor lasers, Laser resonators, Silicon, Silicon photonics, Hybrid silicon lasers

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As demand towards cloud-based services and high-performance computations grows, it imposes requirements on data center performance, and efficiency. Taking advantage of the mature CMOS process technology, and the fact that silicon is the basic material of electronics industry, silicon photonics makes possible production photonic integrated circuits that satisfy these requirements. Here we explore the short-cavity hybrid laser consisting of a III-V amplifier integrated with a silicon photonic crystal (PhC) cavity reflector by so-called butt-coupling approach. The laser possesses great stability characteristics meeting the criteria for data center interconnect applications. The PhC reflector having a Q-factor of 10⁴ at the lasing wavelength 1535 nm can be considered as a narrow-bandwidth filter. The laser demonstrates single mode and eventless operation without any dynamics on the background, and smooth radiofrequency spectrum without evidence of relaxation oscillation frequency. The latter fact is beneficial for many applications, and indicates extremely high damping in PhC laser, where the photon cavity lifetime is greatly improved by the high-Q PhC cavity reflector. We confirm our experimental observations by theory based on delay differential equation model for a single-section semiconductor laser. We reveal the effective damping of the laser, when the detuning between the filter peak and the laser cavity mode is small, and the imaginary parts of the model eigenvalues equal zero. It is possible to undamp the relaxation oscillations forcing self-Q-switched operation in the laser owing to the cumulative action of the alpha-factor and the narrow filter. In conclusion, we experimentally and theoretically demonstrated that relaxation oscillations can be suppressed in the short-cavity semiconductor laser with a narrow intracavity frequency filter. Additionally, on the basis of our analysis we expect the undamping of relaxation oscillations, and self-pulsations when the cavity mode is detuned from the filter peak frequency. The results might be useful for applications in data communications.

Proceedings Article | 4 March 2019 Presentation

Direct frequency modulation of photonic crystal laser by thermal tuning with low-intensity modulation (Conference Presentation)

Sharon Butler, Praveen K. Singaravelu, Andrei Bakoz, Alexandros Liles, Ben O'Shaughnessy, Evgeny Viktorov, Liam O'Faolain, Stephen Hegarty

Proceedings Volume 10923, 109230J (2019) https://doi.org/10.1117/12.2509729

KEYWORDS: Modulation, Photonic crystals, Frequency modulation, Laser crystals, Photonic integrated circuits, Resonators, Reflectivity, Silicon, Reflectors, Electro optics

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Proceedings Article | 9 May 2018 Paper

Frequency modulated external cavity laser with photonic crystal resonator and microheater

Sharon Butler, Andrei Bakoz, Alexandros Liles, Evgeny Viktorov, Liam O'Faolain, Stephen Hegarty

Proceedings Volume 10682, 106822D (2018) https://doi.org/10.1117/12.2319142

KEYWORDS: Modulation, Laser resonators, Photonic crystals, Resonators, Frequency modulation, Silicon, Heterodyning, Semiconductor lasers

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Proceedings Article | 28 April 2016 Paper

Lasing dynamics of photonic crystal reflector laser

Andrei Bakoz, A. Liles, E. Viktorov, L. O'Faolain, T. Habruseva, G. Huyet, S. Hegarty

Proceedings Volume 9892, 989204 (2016) https://doi.org/10.1117/12.2227560

KEYWORDS: Photonic crystals, Optical filters, Semiconductor lasers, Reflectors, Optical amplifiers, Reflectivity, Modulation, Waveguides, Frequency modulation, Reflection

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