Kristina F. Chang, Daniel M. B. Lesko, Carter Mashburn, Peter Chang, Eugene Tsao, Alexander J. Lind, Scott A. Diddams
Abstract
Dual-comb spectroscopy in the ultraviolet (UV) and visible would enable broad bandwidth electronic spectroscopy with unprecedented frequency resolution. However, there are significant challenges in generation, detection, and processing of dual-comb data that have restricted its progress in this spectral region. In this work, we leverage robust 1550 nm few-cycle pulses to generate frequency combs in the UV–visible. We combine these combs with a wavelength multiplexed dual-comb spectrometer and simultaneously retrieve 100 MHz comb-mode-resolved spectra over three distinct harmonics at 386, 500, and 760 nm. The experiments highlight the path to continuous dual-comb coverage spanning 200–750 nm, offering extensive access to electronic transitions in atoms, molecules, and solids.
Bingxin Xu, Zaijun Chen, Theodor W. Hänsch & Nathalie Picqué
Abstract
Ultraviolet spectroscopy provides unique insights into the structure of matter with applications ranging from fundamental tests to photochemistry in the Earth’s atmosphere and astronomical observations from space telescopes1,2,3,4,5,6,7,8. At longer wavelengths, dual-comb spectroscopy, using two interfering laser frequency combs, has become a powerful technique capable of simultaneously providing a broad spectral range and very high resolution. Here we demonstrate a photon-counting approach that can extend the unique advantages of this method into ultraviolet regions where nonlinear frequency conversion tends to be very inefficient. Our spectrometer, based on two frequency combs with slightly different repetition frequencies, provides a wide-span, high-resolution frequency calibration within the accuracy of an atomic clock, and overall consistency of the spectra. We demonstrate a signal-to-noise ratio at the quantum limit and an optimal use of the measurement time, provided by the multiplexed recording of all spectral data on a single photon-counter10. Our initial experiments are performed in the near-ultraviolet and in the visible spectral ranges with alkali-atom vapour, with a power per comb line as low as a femtowatt. This crucial step towards precision broadband spectroscopy at short wavelengths paves the way for extreme-ultraviolet dual-comb spectroscopy, and, more generally, opens up a new realm of applications for photon-level diagnostics, as encountered, for example, when driving single atoms or molecules.
Highly multimode visible squeezed light with programmable spectral correlations through broadband up-conversion
Federico Presutti, Logan G. Wright, Shi-Yuan Ma, Tianyu Wang, Benjamin K. Malia, Tatsuhiro Onodera, Peter L. McMahon
Abstract
Multimode squeezed states of light have been proposed as a resource for achieving quantum advantage in computing and sensing. Recent experiments that demonstrate multimode Gaussian states to this end have most commonly opted for spatial or temporal modes, whereas a complete system based on frequency modes has yet to be realized. Instead, we show how to use the frequency modes simultaneously squeezed in a conventional, single-spatial-mode, optical parametric amplifier when pumped by ultrashort pulses. Specifically, we show how adiabatic frequency conversion can be used not only to convert the quantum state from infrared to visible wavelengths, but to concurrently manipulate the joint spectrum. This near unity-efficiency quantum frequency conversion, over a bandwidth >45 THz and, to our knowledge, the broadest to date, allows us to measure the state with an electron-multiplying CCD (EMCCD) camera-based spectrometer, at non-cryogenic temperatures. We demonstrate the squeezing of >400 frequency modes, with a mean of approximately 700 visible photons per shot. Our work shows how many-mode quantum states of light can be generated, manipulated, and measured with efficient use of hardware resources — in our case, using one pulsed laser, two nonlinear crystals, and one camera. This ability to produce, with modest hardware resources, large multimode squeezed states with partial programmability motivates the use of frequency encoding for photonics-based quantum information processing
Yuk Shan Cheng, Kamalesh Dadi, Toby Mitchell, Samantha Thompson, Nikolai Piskunov, Lewis D. Wright, Corin B. E. Gawith,Richard A. McCracken & Derryck T. Reid
Abstract
Cosmological and exoplanetary science using transformative telescopes like the ELT will demand precise calibration of astrophysical spectrographs in the blue-green, where stellar absorption lines are most abundant. Astrocombs— lasers providing a broadband sequence of regularly-spaced optical frequencies on a multi-GHz grid—promise an atomically-traceable calibration scale, but their realization in the blue-green is challenging for current infrared laser-based technology. Here, we introduce a concept achieving a broad, continuous spectrum by combining second-harmonic generation and sum frequency-mixing in an MgO:PPLN waveguide to generate 390–520 nm light from a 1 GHz Ti:sapphire frequency comb. Using a Fabry-Pérot filter, we extract a 30 GHz sub-comb spanning 392–472 nm, visualizing its thousands of modes on a high-resolution spectrograph. Experimental data and simulations demonstrate how the approach can bridge the spectral gap present in second harmonic-only conversion. Requiring only ≈100 pJ pulses, our concept establishes a new route to broadband UV-visible generation at GHz repetition rates.
Carbon K-Edge Soft X-Rays driven by a 3 µm, 1 kHz OPCPA laser system
Daniel Carlson, Drew Morrill, Will Hettel, Jeremy Thurston, Grzegorz Golba, Daniel Lesko, Scott Diddams, Henry Kapteyn, Margaret Murnane, and Michael Hemmer
Abstract
We report the generation of soft X-ray radiation up to the carbon K-edge (284 eV) in nitrogen gas driven by a millijoule-class 3 µm OPCPA featuring 135 fs pulses at 1 kHz repetition rate.
Compact, ultrastable, high repetition-rate 2 μm and 3 μm fiber laser for seeding mid-IR OPCPA
W. Hettel, G. Golba, D. Morrill, D. Carlson, P. Chang, T.-H. Wu, S. Diddams, H. Kapteyn, M. Murnane, and M. Hemmer
Abstract
We report a compact and reliable ultrafast fiber laser system optimized for seeding a high energy, 2 μm pumped, 3 μm wavelength optical parametric chirped pulse amplification to drive soft X-ray high harmonics. The system delivers 100 MHz narrowband 2 μm pulses with >1 nJ energy, synchronized with ultra-broadband optical pulses with a ∼1 μm FWHM spectrum centered at 3 μm with 39 pJ pulse energy. The 2 μm and 3 μm pulses are derived from a single 1.5 μm fiber oscillator, fully fiber integrated with free-space downconversion for the 3 μm. The system operates hands-off with power instabilities <0.2% over extended periods of time.
Emma Pearce, Nathan R. Gemmell, Jefferson Flórez, Jiaye Ding, Rupert F. Oulton, Alex S. Clark, and Chris C. Phillips
Abstract
Infrared (IR) imaging is invaluable across many scientific disciplines, from material analysis to diagnostic medicine. However, applications are often limited by detector cost, resolution and sensitivity, noise caused by the thermal IR background, and the cost, portability and tunability of infrared sources. Here, we describe a compact, portable, and low-cost system that is able to image objects at IR wavelengths without an IR source or IR detector. This imaging with undetected photons (IUP) approach uses quantum interference and correlations between entangled photon pairs to transfer image information from the IR to a wavelength which can be detected with a standard silicon camera. We also demonstrate a rapid analysis approach to acquire both phase and transmission image information. These developments provide an important step towards making IUP a commercially viable technique.
Thomas Maier, Prof. Dr. Tilman, Prof. Dr. Harald Giessen, Prof. Dr. Günter Wunner
Abstract
The subject of this thesis is the creation of a dipolar quantum gas of dysprosium atoms as well as the investigation of its two-body interactions. For this purpose we setup a new experimental apparatus which allows us to study dipolar many-body systems with ultra-cold bosonic 164Dy, 162Dy as well as fermionic 161Dy atoms. In this work I present our developed cooling and trapping scheme to create a cold sample of dysprosium atoms based on a magneto-optical trap operating at the 626 nm transition and forced evaporative cooling in a crossed optical dipole trap. With our methods we can create Bose-Einstein condensates with N ≈ 25 × 103 (N ≈ 30 × 103) atoms of the 164Dy (162Dy) isotope, respectively. In addition, degenerate Fermi gases with N ≈ 10 × 103 and T/TF ≈ 0.5 can be realized. By comparing the experimentally obtained data with the prediction of theoretical calculations we show that for both bosonic isotopes the dipole-dipole interaction dominates the two-body interaction energy. Furthermore, we observe the effects of the complex atomic structure of dysprosium as a dense and correlated distribution of narrow Feshbach resonances. Despite many narrow resonances we also observe broad resonances which are caused by universal s-wave halo states. These resonances offer the possibility to tune the two-body interactions in dysprosium in a controlled way.
A frequency quintupled laser at 308 nm for spectroscopy of intercombination lines in zinc
Maya Buki, David Roser and Simon Stellmer
Abstract
Many experiments in atomic physics and quantum optics, among them optical atomic clocks, require laser sources in the ultra-violet wavelength range with very low intensity noise and phase noise. The development of such lasers is a challenge, especially when a robust and transportable system is required. Here, we report on the development of a novel continuous wave (cw) frequency quintupled laser at 308 nm with an output power of 0.5 mW, based on a fiber laser operating in the telecom band. Three consecutive frequency conversion stages in nonlinear crystals are employed. The performance of the laser system is demonstrated by linear absorption spectroscopy of a narrow intercombination line in zinc.
Temperature-tunable UV generation using an Alexandrite laser and PPLN waveguides
Goronwy Tawy, Noelia Palomar Davidson, Glenn Churchill, Michael J. Damzen, Peter G. R. Smith, James C. Gates, and Corin B. E. Gawith
Abstract
We present a simple and novel technique for achieving ultra-violet (UV) wavelength-tunable laser operation in the continuous-wave regime. Wavelength tunable operation in the near infrared is obtained from a compact two-mirror Alexandrite laser cavity by temperature tuning of the laser crystal. Second-harmonic-generation to the UV is then achieved at 376-379 nm and 384-386 nm by temperature tuning of a periodically-poled lithium-niobate (PPLN) waveguide. A maximum UV power of 1.3 mW from 185 mW infra-red pump throughput is obtained from a third-order PPLN Λ=6.1um grating. These results show promising potential for simple and wavelength tunable access to wavelengths at 360-400 nm.
