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We generate a 200-nm optical frequency comb at 1.5 microns by injecting two single-frequency lasers into a highly nonlinear fiber, and explore its spectral phase properties and high power to demonstrate full nonlinear conversion into its…

Terahertz (THz) near-field imaging is a flourishing discipline [1], with applications from fundamental studies of beam propagation [2,3] to the characterisation of metameterials [4,5] and waveguides [6,7]. Beating the diffraction limit…

Optical frequency combs have had a remarkable impact on precision spectroscopy. Enabling this technology in the x-ray domain is expected to result in wide-ranging applications, such as stringent tests of astrophysical models and quantum…

Near-field imaging with terahertz (THz) waves is emerging as a powerful technique for fundamental research in photonics and across physical and life sciences. Spatial resolution beyond the diffraction limit can be achieved by collecting THz…

Frequency combs, spectra of evenly-spaced narrow phase-coherent laser lines, have revolutionized precision measurements. On-chip frequency comb generators hold much promise for fully-integrated instruments of time and frequency metrology.…

We report on experimental and theoretical demonstration of an optical comb spectrum based on a combination of cascaded stimulated Raman scattering and four-wave mixing mediated by Raman-induced nonresonant Kerr-type nonlinearity. This…

The mid-infrared spectral range (2 to 20 \mu m) is of particular importance for chemistry, biology and physics as many molecules exhibit strong ro-vibrational fingerprints. Frequency combs - broad spectral bandwidth coherent light sources…

Terahertz (THz) frequencies are important for next generation wireless systems due to the advantages in terms of large available bandwidths. On the other hand, the limited range due to high attenuation in these frequencies can be overcome…

Signal Processing · Electrical Eng. & Systems 2024-05-31 Hasan Nayir , Erhan Karakoca , Güneş Karabulut Kurt , Ali Görçin

The femtosecond laser frequency comb has enabled the 21st century revolution in optical synthesis and metrology. A particularly compelling technique that relies on the broadband coherence of two laser frequency combs is dual-comb…

Optics · Physics 2023-07-19 Vicente Duran , Santiago Tainta , Victor Torres-Company

Optical frequency combs generated by multiple four-wave mixing of two stabilized single-frequency lasers in optical fibers are proposed for use as high precision frequency markers, calibration of astrophysical spectrometers and metrology.…

Optics · Physics 2009-11-13 Flavio C. Cruz

Terahertz quantum cascade lasers (THz QCLs) are chip-scale semiconductor lasers operating in the frequency range between 1-6 THz, useful as compact sources for spectroscopy, communications, and non-destructive imaging and testing. Here, we…

The search for earth-like exoplanets with the Doppler radial velocity technique is an extremely challenging and multifaceted precision spectroscopy problem. Currently, one of the limiting instrumental factors in reaching the required…

Fourier transform spectroscopy based on incoherent light sources is a well-established tool in research fields from molecular spectroscopy and atmospheric monitoring to material science and biophysics. It provides broadband molecular…

Large multiple antenna arrays coupled with accurate beamforming are essential in terahertz (THz) communications to ensure link reliability. However, as the number of antennas increases, beam alignment (focusing) and beam tracking in mobile…

Systems and Control · Electrical Eng. & Systems 2025-11-04 Irched Chafaa , E. Veronica Belmega , Giacomo Bacci

This article focuses on the near-field effect in terahertz (THz) communications and sensing systems. By equipping with extremely large-scale antenna arrays (ELAAs), the near-field region in THz systems can be possibly extended to hundreds…

Information Theory · Computer Science 2023-06-19 Zhaolin Wang , Xidong Mu , Yuanwei Liu

Accelerated by the increasing attention drawn by 5G, 6G, and Internet of Things applications, communication and sensing technologies have rapidly evolved from millimeter-wave (mmWave) to terahertz (THz) in recent years. Enabled by…

Signal Processing · Electrical Eng. & Systems 2023-09-19 Josiah W. Smith , Murat Torlak

Optical frequency comb, as a spectrum made of discrete and equally spaced spectral lines, is a light source with essential applications in modern technology. Cavity optomechanical systems were found to be a feasible candidate for realizing…

Optics · Physics 2024-08-13 Xin Gu , Jinlian Zhang , Shulin Ding , Xiaoshun Jiang , Bing He , Qing Lin

Terahertz frequency bands will likely be used for the next-generation wireless communication systems to provide data rates of hundreds of Gbps or even Tbps because of the wide swaths of unused and unexplored spectrum. This paper presents…

Information Theory · Computer Science 2021-10-26 Yunchou Xing , Theodore S. Rappaport

Terahertz (THz) communication is widely considered as a key enabler for future 6G wireless systems. However, THz links are subject to high propagation losses and inter-symbol interference due to the frequency selectivity of the channel.…

Information Theory · Computer Science 2021-02-16 Konstantinos Dovelos , Michail Matthaiou , Hien Quoc Ngo , Boris Bellalta

We present a terahertz time-domain spectroscopy (THz-TDS) system which accesses a broadband spectrum, efficiently covering the so-called "new THz gap" between 5 and 15 THz and extending beyond 25 THz. The system exploits nonlinear…