• Physics and Astronomy Colloquium

May 2, 2025 3:30 PM - May 2, 2025 4:30 PM
PAIS 1100

Host:

Alex Albrecht

Presenter:

Ursula Keller (ETH Zurich, Switzerland)

Zoom link

The optical frequency comb (OFC) revolution began in the late 1999, marked by three pivotal publications [1-3]. Since then, the field has been a major focus of research, continuously evolving with new innovations. A key advancement are dual-comb single-cavity lasers, which employ a pair of combs distinguished by a small yet precise difference in their spacing. This allows for rapid pump-probe, spectroscopy and sub-μm long-distance LiDAR measurements without any mechanical delay lines and without any stabilization of the laser cavity.

For this advancement we have invented new shared-cavity methods to generate two optical combs with slightly different, adjustable pulse repetition rates. By generating both combs within the same cavity, the system is simplified, and the combs exhibit highly correlated noise properties. These single-cavity dual-comb lasers achieve low noise levels, making them suitable for practical dual-comb measurements. We pioneered two techniques based on polarization [4] and spatial [5] multiplexing. In 2017, the polarization multiplexing approach enabled dual-comb spectroscopy from a single free-running passively mode-locked laser cavity, a key milestone [6].

Since then, we have demonstrated low-noise performance using diode-pumped Yb-doped solid-state and vertical-emitting semiconductor lasers. To verify these low-noise properties, we developed a highly sensitive pulse timing jitter characterization tool [7]. We have demonstrated coherent averaging of dual-comb signals, enabling dual-comb spectroscopy applications with excellent signal-to-noise ratios from free-running dual-comb oscillators without additional stabilization [8]. Many application demonstrations have been done with these lasers, such as picosecond ultrasonics [9], time-domain THz spectroscopy [10], equivalent sampling of SESAM response [11], spectroscopy with adjustable delay intervals [12], 3D microscopy [13], OPO and mid-IR spectroscopy [14] bio-medical applications [15], broadband hyperspectral LiDAR [16] and long-range LiDAR for interferometric tracking of moving targets [17].

This talk will provide an introduction to dual-comb lasers and highlight some specific application demonstrations.

[1] H. Telle et al., Appl. Phys. B 69, 327–332 (1999)

[2] A. Apolonski et al., Phys. Rev. Lett. 85, 740–743 (2000)

[3] D. J. Jones et al., Science 288, 635–639 (2000)

[4] S. M. Link et al., Optics Express 23 (5), 5521 (2015)

[5] J. Pupeikis et al., Optica 9 (7), 713 (2022)

[6] S. M. Link et al., Science, 356, 1164 (2017)

[7] S. L. Camenzind et al., Opt. Express 30 (4), 5075 (2022)

[8] C. R. Phillips et al., Opt. Express 31 (5), 7103 (2023)

[9] J. Pupeikis et al., Photoacoustics 29, 100439 (2023)

[10] B. Willenberg et al., Applied Optics 63 (15), 4144 (2024)

[11] A. Nussbaum-Lapping et al., Applied Physics B 128, 24 (2022)

[12] F. Flöry et al., Ultrafast Science 3, 0027 (2023)

[13] W. Lu et al., Optics Letters 49 (7), 1766 (2024)

[14] C. P. Bauer et al., Nature Communications 15, 7211 (2024)

[15] B. Zhang et al., ACS Photonics 11 (10), 3972 (2024)

[16] S. L. Camenzind et al., Optics Letters 50 (4), 1289 (2025)

[17] S. L. Camenzind et al., https://arxiv.org/abs/2411.05585