Mario Siciliani de Cumis

Classical Signature of Ponderomotive Squeezing in a Suspended Mirror Resonator

The radiation pressure coupling between a low-mass moving mirror and an incident light field has been experimentally studied in a high-finesse Fabry-Perot cavity. Using classical intensity noise in order to mimic radiation pressure quantum fluctuations, the physics of ponderomotive squeezing comes into play as a result of the opto-mechanical correlations between the field quadratures. The same scheme can be used to probe ponderomotive squeezing at the quantum level, thus opening new routes in quantum optics and high sensitivity measurement experiments.

Photothermal and thermo-refractive effects in high reflectivity mirrors at room and cryogenic temperature

Increasing requirements in the sensitivity of interferometric measurements is a common feature of several research fields, from gravitational wave detection to quantum optics. This motivates refined studies of high reflectivity mirrors and of noise sources that are tightly related to their structure. In this work we present an experimental characterization of photothermal and thermo-refractive effects in high reflectivity mirrors, i.e., of the variations in the position of their effective reflection plane due to weak residual power absorption. The measurements are performed by modulating the impinging power in the range 10Hz÷100kHz. The experimental results are compared with an expressly derived theoretical model in order to fully understand the phenomena and exploit them to extract useful effective thermo-mechanical parameters of the coating. The measurements are extended to cryogenic temperature, where most high sensitivity experiments are performed (or planned in future versions) and where characteriza...

Radiation pressure excitation and cooling of a cryogenic micro-mechanical systems cavity

We describe an experiment achieving radiation pressure excitation and cooling of a mechanical mode in a cryogenic Fabry–Perot cavity with a micromechanical oscillator [micro-electro-mechanical systems (MEMS)] as end mirror. The response function to periodic modulations of the intracavity power provides an independent measurement of the effective modal mass allowing an accurate estimate of the mode temperature from the corresponding displacement noise spectrum. We also obtained optical cooling of the MEMS fundamental mode at 110 kHz from 11 to 4.4 K, limited only by the optical Finesse and the mechanical quality of the system. These results represent a step toward the observation of quantum optomechanical effects and motivate further experiments with improved performances of the MEMS samples.

MAGNETIC MICROTRAPS FOR QUANTUM CONTROL

We will review the realization of magnetic microtraps for ultracold atoms. Such devices combine experimental simplicity with unsurpassed versatility in designing confining potentials. We will show how combining magnetic microtraps with optical lattices one can realize many possible quantum systems of interest in many fields ranging from solid state physics to condensed matter. We will also illustrate new possibilities in the quantum simulation of different physical systems.

Whispering gallery mode stabilization of quantum cascade lasers for infrared sensing and spectroscopy

Narrow-linewidth lasers are key elements in optical metrology and spectroscopy. From their spectral purity, the measurements accuracy and the overall quality of collected data critically depend. Crystalline micro-resonators have undergone an impressive development in the last decade, opening new ways to photonics from the mm to the μm scale. Their wide transparency range and high Q-factor make them suitable for integration in compact apparatuses for precision spectroscopy from the visible to the mid-IR. Here, we present our recent results on frequency stabilization and linewidth narrowing of quantum cascade lasers using crystalline Whispering Gallery Mode Resonators for mid-IR precision spectroscopy.

Characteristic vibrational frequencies of toxic polychlorinated dibenzo-dioxins and -furans.

The possibility to monitor in real-time the emission of dioxins produced by incineration of waste or by industrial processes is nowadays a necessity considering the high toxicity of these compounds, their persistence in the environment and their ability to bio-accumulate in the food chain. Recently it has been demonstrated the potentiality of detecting dioxins in carbon tetrachloride via MIR Quantum Cascade Lasers. A fundamental step in real time monitoring of dioxins emission is the possibility to recognize the most toxic congeners within complex mixtures and at low concentrations. Taking into account the lack of spectroscopic data about these very toxic environmental pollutants and the necessity to monitor their emissions we have recorded infrared spectra of 13 of the 17 most toxic congeners of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo-furans (PCDFs) dissolved in carbon tetrachloride. In this way we have obtained a small database that we have used to test the ability of a linear regression algorithm to recognize each congener and its relative concentration in complex mixtures of these compounds.

Interferometric Quantum Sensors

Optical interferometric sensors represent the most advanced measurement tools in terms of precision and sensitivity for position detection. Micro-mechanical and micro-optical active and passive devices can be realized with present technologies on integrable substrates such as silicon wafers. We are working on the fabrication and characterization of micromirrors realized with micromachining technique. Our goal is to realize structures with a mechanical resonance frequency in ranges 1 kHz – 100 kHz and 1 MHz – 100 MHz. In these ranges we can think of different applications above all in the detection of gravitational waves and in quantum computation.

QCL-based frequency metrology from the mid-infrared to the THz range: a review

Abstract Quantum cascade lasers (QCLs) are becoming a key tool for plenty of applications, from the mid-infrared (mid-IR) to the THz range. Progress in related areas, such as the development of ultra-low-loss crystalline microresonators, optical frequency standards, and optical fiber networks for time and frequency dissemination, is paving the way for unprecedented applications in many fields. For most demanding applications, a thorough control of QCLs emission must be achieved. In the last few years, QCLs’ unique spectral features have been unveiled, while multifrequency QCLs have been demonstrated. Ultra-narrow frequency linewidths are necessary for metrological applications, ranging from cold molecules interaction and ultra-high sensitivity spectroscopy to infrared/THz metrology. A review of the present status of research in this field is presented, with a view of perspectives and future applications.

Microcavity-stabilized quantum cascade laser

A CaF2 whispering gallery mode microresonator is used for frequency stabilization and linewidth narrowing of a mid-IR quantum cascade laser. Sub-Doppler recording of a CO2 transition demonstrates the suitability of the system for high-resolution spectroscopy.

Quartz-enhanced photoacoustic sensors for H2S trace gas detection

We report on three different quartz enhanced photoacoustic (QEPAS) sensors operating in the near-IR, mid-IR and THz spectral ranges, employing quartz tuning forks of different sizes and shapes. To test our sensors in the near-IR we used a diode laser working at 2.7 μm, while in the mid-IR we employed a quantum cascade laser (QCL) operating at 7.9 μm, fiber-coupled to the QEPAS cell. In the THz range we employed a QCL emitting at 2.95 THz. H2S absorption features with line-strength up to 10-20 cm/mol were selected and QEPAS normalized noise-equivalent absorption in the 10-10 W•cm-1•Hz-1/2 range was achieved..