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Integrated-photonics microchips now enable a range of advanced functionalities for high-coherence applications such as data transmission, highly optimized physical sensors, and harnessing quantum states, but with cost, efficiency, and…
The advent of the laser frequency comb as the wavelength calibration unit allows us to measure the radial velocity at $cm\ s^{-1}$ precision level with high stability in long-term, which enable the possibility of the detection of…
Tunable lasers, with the ability to continuously adjust their emission wavelengths, have found widespread applications across various fields such as biomedical imaging, coherent ranging, optical communications and spectroscopy. In these…
Self-heterodyne fiber interferometers have been shown to be capable of stabilizing lasers to ultra-narrow linewidths and present an excellent alternative to high finesse cavities for frequency stabilization. In addition to suppressing…
Laser frequency combs (LFCs) are an important component of Doppler radial velocity (RV) spectroscopy that pushes fractional precision to the $10^{-10}$ level, as required to identify and characterize Earth-like exoplanets. However, large…
Dual-comb spectroscopy has emerged as an indispensable analytical technique in applications that require high resolution and broadband coverage within short acquisition times. Its experimental realization, however, remains hampered by…
Spectroscopy methods often require calculating the central frequency of a resonance line, that is usually implemented by finding a best fit to the spectrum by a line-shape function. Such an iterative procedure is slow and requires an…
The use of averaging has long been known to reduce noise in statistically independent systems that exhibit similar levels of stochastic fluctuation. This concept of averaging is general and applies to a wide variety of physical and man-made…
Laser frequency combs (LFCs) are well on their way to becoming the next-generation calibration sources for precision astronomical spectroscopy. This development is considered key in the hunt for low-mass rocky exoplanets around solar-type…
Improvements to dual-comb interferometers will benefit precision spectroscopy and sensing, distance metrology, tomography, telecommunications etc. A specific requirement of such interferometers is to enforce mutual coherence between the two…
One of the essential prerequisites for detection of Earth-like extra-solar planets or direct measurements of the cosmological expansion is the accurate and precise wavelength calibration of astronomical spectrometers. It has already been…
Ultra-stable lasers and optical frequency combs have been the enabling technologies for the tremendous progress of precise optical spectroscopy in the last ten years. To improve laser frequency stabilization beyond the thermal-noise…
Many atomic and molecular systems of fundamental interest possess resonance frequencies in the extreme ultraviolet (XUV) where laser technology is limited and radiation sources have traditionally lacked long-term phase coherence. Recent…
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 telescopes. At longer…
We have performed sub-Doppler spectroscopy on the narrow intercombination line of cold calcium atoms using the amplified output of a femtosecond laser frequency comb. Injection locking of a 657-nm diode laser with a femtosecond comb allows…
We devise a new detection technique for mid-infrared multi-heterodyne spectroscopy. As an experimental implementation, mid-infrared light interrogates a gas sample in the 3-$\mu$m region of the fundamental CH, OH, NH stretch in molecules…
We present a system for molecular spectroscopy using a broadband mid-infrared laser with near infrared detection. Difference frequency generation of a Yb:fiber femtosecond laser produced a mid-infrared (MIR) source tunable from 2100-3700…
We report absolute frequency measurements of the molecular iodine P(46) 5-4 $a_{1}$, $a_{10}$, and $a_{15}$ hyperfine transitions at 647 nm with a fiber-based frequency comb. The light source is based on a Littrow-type external-cavity diode…
Aims. In this article we aim to show how the gradient of the thermal millimetre continuum spectrum, as emitted from the quiet solar atmosphere, may be used as a diagnostic for the optical thickness regime at the centre of the observing…
A phase-stabilized femtosecond laser comb is directly used for high-resolution spectroscopy and absolute optical frequency measurements of one- and two-photon transitions in laser-cooled \rb atoms. Absolute atomic transition frequencies,…