arXiv subjects

Dario Giannotti

Publications and source records attributed to Dario Giannotti.

6 recordsLinked to original sources

arXiv2026

Octave-spanning 10-GHz Er-doped solid-state optical frequency comb

Optical frequency combs provide a phase-coherent interface between optical and microwave domains, underpinning advances in precision metrology, spectroscopy, and time-frequency transfer. Most conventional comb architectures are limited to sub-gigahertz repetition rates, constraining integration and scalability. Here, we demonstrate a compact, 10-GHz Er-doped solid-state frequency comb operating near the 1550 nm telecommunications window. The system, assembled entirely from commercially available components, produces a coherent spectrum spanning from 1150 nm to 2350 nm with exceptionally low intensity and phase noise. Full frequency stabilization of both pulse repetition and carrier envelope offset frequencies is demonstrated with respect to an RF reference. Comprehensive characterization reveals performance exceeding that of previously reported solid-state combs in power-per-mode and noise suppression. These results establish a robust and accessible platform for multi-gigahertz-repetition-rate comb synthesis, bridging laboratory-grade performance with practical deployment in optical communication, precision timing, and astronomical instrumentation.

physics.optics↗

arXiv2025

Generation and detection of squeezed states via a synchronously pumped optical parametric oscillator

A synchronously pumped optical parametric oscillator (SPOPO) operating at 93 MHz is used to generate squeezed states at 1035 nm. The system features a counter-propagating beam at the same wavelength as the quantum state, which simultaneously actively stabilizes the cavity and, after transmission, acts as the local oscillator for homodyne detection. By deriving the local oscillator directly from the SPOPO cavity, the setup establishes an intrinsically excellent spatial mode overlap and high interference visibility, forming a distinctive self-referenced architecture. Two spatial light modulators enable precise spectral shaping of both the pump and the local oscillator in amplitude and phase, allowing investigation of the spectral properties of the generated states. The versatility of the setup further allows exploration of different SPOPO configurations, including regimes with varied finesse and escape efficiency. Representative measurements, including homodyne traces and squeezing levels as functions of pump power and local oscillator bandwidth, demonstrate the performance of the system. Theoretical simulations based on a multimode singular-value-decomposition model reproduce well the measured dependence of squeezing on pump power and LO bandwidth, confirming the accuracy of the description and the robustness of the setup. Measured squeezing levels up to -3.3 dB are achieved, corresponding to -5.7 dB at SPOPO output, evidencing the robustness and versatility of this platform for stable pulsed squeezed-light generation and advanced quantum optical applications.

quant-ph↗

arXiv2025

Few-cycle THz Pulse Generation in DSTMS Crystal Pumped by a 8.3-MHz Amplified Mamyshev Oscillator

Mamyshev oscillators are an emerging class of ultrafast fiber lasers that support exceptionally broadband spectra and few-femtosecond pulse durations, making them well-suited for nonlinear frequency conversion. Despite this potential, THz generation using Mamyshev oscillators has not been demonstrated to date. In this work, we report the generation of THz few-cycle at 8.3 MHz repetition rate via optical rectification of a 31-fs pulse duration, 1-W average power amplified Mamyshev oscillator in a 190-um-thick DSTMS organic crystal. We measured a THz average power of 40 uW and a spectral bandwidth of 4 THz. To further investigate the advantage of combining Mamyshev oscillator and organic crystals for THz generation at multi-MHz repetition rate, we compared the THz pulses with those generated using a conventional inorganic 500 um-thick GaP crystal, obtaining comparable bandwidth, but 20 times lower power with respect to DSTMS.

physics.optics↗

arXiv2025

Ytterbium-laser-driven THz generation in thin lithium niobate at 1.9 kW average power in a passive enhancement cavity

Single-cycle, high-power, high-repetition-rate THz pulse sources are becoming the cornerstone of several scientific and industrial applications. A promising and versatile method for high-power THz generation is optical rectification in nonlinear crystals pumped by powerful near-infrared ultrafast laser systems. In this context, ytterbium-based laser sources are particularly advantageous in terms of power scalability and technology establishment. However, as the repetition rate increases toward hundreds of MHz, the conversion efficiency typically decreases, as most laser systems do not reach sufficiently high average power to correspondingly enhance the peak power to drive the nonlinear conversion process efficiently. An alternative approach to achieving sufficiently high average power at high repetition rate is based on passive enhancement cavities, which boost the pulse energy of standard watt-level ytterbium lasers by orders of magnitude. We present the first demonstration of optical rectification in a passive enhancement cavity at multi-kW levels, achieved by a 240-fold power enhancement. By irradiating a 50-$μ$m thin lithium niobate plate with 1.9-kW average power inside the enhancement cavity, we generate milliwatt-level THz pulses with 2-THz bandwidth and 93-MHz repetition rate, mostly limited by the driving pulse duration. To the best of our knowledge, this represents the highest driving average power used for OR. This methodology represents a promising new step towards high-repetition-rate and high average power single-cycle THz sources using widely available multi-watt level Yb lasers.

physics.optics↗

arXiv2022

Low frequency-to-intensity noise conversion in a pulsed laser cavity locking by exploiting Carrier-Envelope Offset manipulation

We report on the dependence of the frequency-to-intensity noise conversion in the locking of an ultrafast laser against a high-finesse optical resonator from the Carrier Envelope Offset (CEO) frequency. By a proper combination of the cavity finesse and laser CEO frequency it is possible to optimize the signal-to-noise ratio of the laser intensity trapped into the optical resonator. The theoretical description of the problem together with the numerical simulations and experimental results are presented with the aim of a strong suppression of the intensity fluctuations of the trapped laser field.

physics.optics↗

arXiv2021

A new method for spatial mode shifting of a stabilized optical cavity for the generation of dual-color X-rays

We propose an innovative method to shift the transversal position of the focal point of an optical cavity keeping it actively stabilized. Our cavity is a 4 mirrors bow-tie cavity and the spatial shift of the resonant mode is obtained by properly rotating the two curved mirrors by piezo actuators. This method allows us to move the transversal position of the cavity focal point of $135 μm$ in a time of $50 ms$, keeping the resonance condition of the cavity by means of the Pound-Drever-Hall technique. We propose to use this technique for the generation of 2-color X-rays via Inverse Compton Scattering (ICS). This technique exploits the large average power stored in the high finesse cavity by shifting the laser beam with respect to the electron beam trajectory, hence controlling the spatial superposition of the electron and photon beams in the interaction region. Arranging two cavities assembled one on top of the other, with different collision angle with the electron beam, allows the generation of X-ray bursts of different energies just by swiftly moving the two cavities, switching the two focal points onto the electron beam trajectory, thus activating in sequence two different ICS spectral lines.

physics.optics↗