HAL Portal IOGS (nstitut d'Optique Graduate School)
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Chirped pulse upconversion for femtosecond mid-infrared spectroscopy at 100 kHz
No full textInternational audienceWe demonstrate that chirped pulse up-conversion (CPU), a method routinely used with systems based on 1-kHz Titanium:Sapphire lasers, can be extended to a repetition rate of 100 kHz with an Ytterbium diode-pumped femtosecond amplifier. Individual mid-infrared spectra can thus be measured directly in the near infrared using a fast CMOS linescan camera. After an appropriate Fourier processing, a spectral resolution of 1.1 cm-1 is reported, currently limited by our spectrometer. Additionally, we demonstrate the application of CPU to a pump-probe measurement of the vibrational relaxation in carboxy-hemoglobin, and we show that the combination of fast scanning and fast acquisition enables a straightforward removal of pump scattering interference
A contextually objective approach to the extended Wigner's friend thought experiment
No full textInternational audienceWe present a discussion of the extended Wigner's friend thought experiment proposed by Frauchiger and Renner in [1]. We show by using various arguments, including textbook quantum mechanics and the ontological approach of Contexts, Systems, Modalities (CSM), that no contradiction arises if one admits that agents must agree on what is considered as a system and what is not. In such a contextually objective approach of quantum mechanics, the apparent contradiction is automatically removed. We also discuss why this mutual agreement between agents is already implicit in the standard formulations of quantum mechanics, and why removing it leads to inconsistencies
Impact of the flicker noise on the ring oscillator-based TRNGs
No full textInternational audienceRing Oscillators (RO) are often used in true random number generators (TRNG). Their jittered clock signal, used as randomness source, originates from thermal and flicker noises. While thermal noise jitter is generally used as the main source of randomness, flicker noise jitter is not due to its autocorrelation. This work aims at qualitatively settling the issue of the influence of flicker noise in TRNGs, as its impact increases in newer technology nodes. For this, we built a RO behavioural model, which generates time series equivalent to a jittered RO signal. It is then used to generate the output of an elementary RO-TRNG. Despite general expectations, the autocorrelation inside the output bit stream is reduced when the amplitude of flicker noise increases. The model shows that this effect is caused by the sampling of the jittered signal by the second oscillator, which hides the behaviour of the absolute jitter, causes resetting of the perceived phase, and suppresses any memory effect. The inclusion of flicker noise as a legitimate noise source can increase the TRNG output bit rate by a factor of four for the same output entropy rate. This observation opens new perspectives towards more efficient stochastic models of the RO-TRNGs
Thermal Characterization of Electronic Power Component: a comparison between resistive and fiber Bragg grating sensors
No full textInternational audienceThe operating temperature can be critical in some electronic circuits to ensure the integrity and proper functioning of a circuit, especially in power electronics. A temperature mapping can then be useful to anticipate the malfunction. The objective of this paper is to set up methods to study the thermal behavior of power electronic components such as inductors and transformers. Two methods are compared: a first one based on resistive integrated sensors and a second one based on fiber Bragg grating sensors. The analysis of each method is divided into two parts: the calibration of the sensor and the validation of the procedure
Exact Maxwell evolution equation of resonator dynamics: temporal coupled-mode theory revisited
No full textInternational audienceDespite its widespread significance, the temporal coupled-mode theory (CMT) lacks a foundational validation based on electromagnetic principles and stands as a phenomenological theory relying on fitted coupling coefficients. We employ an ab initio Maxwellian approach using quasinormal-mode theory to derive an “exact” Maxwell evolution (EME) equation for resonator dynamics. While the resulting differential equation bears resemblance to the classical one, it introduces novel terms embodying distinct physics, suggesting that the CMT predictions could be faulted by dedicated experiments, for instance carried out with short and off-resonance pulses, or with resonators of sizes comparable to or greater than the wavelength. Nonetheless, our examination indicates that, despite its inherent lack of strictness, the CMT enables precise predictions for numerous experiments due to the flexibility provided by the fitted coupling coefficients. The new EME equation is anticipated to be applicable to all electromagnetic resonator geometries, and the theoretical approach we have taken can be extended to other wave physics
Designing electromagnetic resonators with quasinormal modes
No full textInternational audienceMicro- and nanoresonators, which enable light trapping in small volumes for extended durations, play a crucial role in modern photonics. The optical response of these resonators is determined by their fundamental resonances, known as quasinormal modes (QNMs). Over the past decade, the electromagnetic theory of QNMs has undergone significant development and has now reached a level of maturity that allows its reliable application to numerous contemporary electromagnetic problems. In this review, we explore recent applications of QNM theory for designing and understanding micro and nanoresonators. We highlight why QNMs provide deep physical insights and enhance computational efficiency in scenarios involving mode hybridization and perturbation
TrustSoC-V: An Heterogeneous SoC Architecture for RISC-V, Secure-by-Design
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Shaped Constellation Continuous Variable Quantum Key Distribution: Concepts, Methods and Experimental Validation
No full textInternational audienceQuantum key distribution (QKD) enables the establishment of secret keys between users connected via a channel vulnerable to eavesdropping, with information-theoretic security, that is, independently of the power of a malevolent party (Scarani et al., 2009). QKD systems based on the encoding of the key information on continuous variables (CV), such as the values of the quadrature components of coherent states (Weedbrook et al., 2012), (Diamanti and Leverrier, 2015), present the major advantage that they only require standard telecommunication technology. However, the most general security proofs for CV-QKD required until now the use of Gaussian modulation by the transmitter, complicating practical implementations (Jouguet et al., 2013), (Zhang et al., 2020), (Jain et al., 2022). Here, we experimentally implement a protocol that allows for arbitrary, Gaussian-like, discrete modulations, whose security is based on a theoretical proof that applies generally to such situations (Denys et al., 2021). These modulation formats are compatible with the use of powerful tools of coherent optical telecommunication, allowing our system to reach an estimated performance of tens of megabit per second secret key rates over 25 km.</div
A Tunable Isolator Based on Coplanar High Impedance Wire
No full textInternational audienceIn this paper we propose a tunable isolator based on coplanar waveguide (CPW) realized on yttrium iron garnet (YIG) substrate. One of grounds planes of the CPW is periodically loaded with short-circuited slots. With an in-plane DC magnetic field perpendicular to the direction of the propagation, the structure leads to a non-reciprocal propagation at a resonant frequency that can be tuned in Ku band. The resonant frequency is tunable either magnetically by tuning the DC magnetic bias field, or mechanically by suspending a copper plate at an adjustable distance above the structure. Under a low magnetic bias field of 70 Oe, the operating frequency can be tuned mechanically from 13.6 to 15.15 GHz. A tuning frequency range of 2 GHz. We show here the interest of the mechanical tuning over magnetical one.This tunable isolator exhibits a great potential for RF applications and can be easily implemented in different microwave devices for reconfigurable RF applications