Femtosecond Er-doped fiber laser source tunable from 872 to 1075 nm for two-photon vision studies in humans

Dorota Stachowiak; Marcin Marzejon; Jakub Bogusławski; Zbigniew Łaszczych; Katarzyna Komar; Maciej Wojtkowski; Grzegorz Soboń

doi:10.1364/BOE.452609

Femtosecond Er-doped fiber laser source tunable from 872 to 1075 nm for two-photon vision studies in humans

Biomed Opt Express. 2022 Mar 4;13(4):1899-1911. doi: 10.1364/BOE.452609. eCollection 2022 Apr 1.

Authors

Dorota Stachowiak¹, Marcin Marzejon^{2

3}, Jakub Bogusławski^{1

2

4}, Zbigniew Łaszczych¹, Katarzyna Komar^{2

4

5}, Maciej Wojtkowski^{2

4}, Grzegorz Soboń¹

Affiliations

¹ Laser & Fiber Electronics Group, Faculty of Electronics, Photonics and Microsystems, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland.
² Department of Physical Chemistry of Biological Systems, Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
³ Department of Metrology and Optoelectronics, Faculty of Electronics, Telecommunications and Informatics, Gdańsk University of Technology, G. Narutowicza 11/12, 80-233 Gdańsk, Poland.
⁴ International Centre for Translational Eye Research, Skierniewicka 10a, 01-230 Warszawa, Poland.
⁵ Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziądzka 5, 87-100 Toruń, Poland.

Abstract

We report the development of a widely-tunable femtosecond fiber laser system and its application for two-photon vision studies. The source is based on an Er-doped fiber laser with spectral shift up to 2150 nm, followed by a second harmonic generation module to generate a frequency-doubled beam tunable from 872 to 1075 nm. The source delivers sub-230 fs pulses with nearly-constant duration over the entire tuning range, with output powers between 0.68-1.24 mW, which corresponds to a pulse energy of 13.2-24.1 pJ. Such pulse energy is sufficient for employing a system for measurements of two-photon scotopic spectral sensitivity of two-photon vision in humans. The laser parameters allow for very efficient and safe two-photon stimulation of the human visual system, as proved by a good separation between one- and two-photon thresholds for wavelengths below 950 nm, which we have confirmed for 3 healthy subjects.