⮞ Équipe DOP ⮞ Thématiques de recherche ⮞ Activité « Optique hyperfréquences et THz » ⮞

Presentation

The interference of two laser carriers on the same transverse mode and on the same polarization produces, on a photodetector, a the frequency difference between the two carriers. Manipulations combining photonic and electronic techniques make it possible to have very tunable and very pure beating signals.

Dual-polarization lasers

The DOP team demonstrated in 2001 the capabilities of dual-frequency solid state Er3+ and Nd3+ lasers to produce beatings tunable in frequency around 1 THz with very high spectral finesse.

Dual-polarization Ti:Sa laser

The Ti:Sa laser emits radiation at 800 nm; the beat is then convertible with an AsGa LT photodetector into microwave, millimeter or sub-millimeter radiation. We have implemented a dual-frequency dual-polarization single-mode longitudinal laser for each of the polarizations, with particular attention to thermal drift[F1, F2]. Without servo-control, our laser source shows a beat drift of less than a hundred kHz over a day.

Dual-polarization Er:glass laser

In the frame of theOSMOTUS[F3] project, we have created and designed a dual-frequency bi-polarization Er:Glass laser emitting at wavelengths of 1.55µm, compatible with InGaAs, UTC or PIN photodiodes. Since the frequencies are locked on an ultra-stable cavity in crossed polarizations, the beating has a phase noise independent of the beat frequency. We have observed a phase noise at 10GHz better than the noise floor of the measurement bench.

Implémentation d’une synthèse de fréquence ultra-stable par des lasers à état solide à 1,5 μm.

Continuously tunable synthesizer 0-850 GHz

We have designed and produced a frequency synthesizer using fiber optic components for optical telecommunications. Two DFB lasers are locked in crossed polarizations on a fiber cavity. We have shown that the beat frequency noise is independent of the beat frequency up to 96GHz. By adjusting the temperature of the lasers, we precisely control the resonance index. A phase-locked loop allows continuous frequency tuning. The entire device can be controlled by a computer, allowing control compatible with submillimeter spectroscopy.

Fig. 1 – instrument scheme. The beating of two laser diodes stabilized in crossed polarizations on a common reference allows a large frequency excursion and the accuracy of the synthesized frequency. An antenna converts the beat into a free space wave. The spectroscopy cell (50 cm optical path) can analyze the molecules of a gas mixture or the gases dissolved in a liquid or solid sample.
Fig. 2 – Frequency synthesis details. Left: commercial fiber optic elements for optical telecommunications
right: electronic, with stabilizations inspired by those of the Virgo project. We demonstrated a record linewidth of 30 Hz.

Financial support

  • FP7, projet “nexpresso” : FP7-ICT-258178, “”Tunable high resolution Ti:Sa dual frequency laser for CW THz oscillator”, partenariat avec Resolution Spectra Systems
  • ANR-15-CE24-004, « Émetteur térahertz photonique reposant sur un photomélangeur hautement distribué excité par un laser bifréquence — PHENIX », partenariat avec IEMN à Lille.
  • ANR-11-BS03-0010, « Oscillateur micro-onde à THz Ultra-stable — OSMOTUS», partenariat avec IEMN Lille, Thales TRT, ARTEMIS Nice.
  • CNRS MITI « source submillimétrique accordable pour la détection du métabolisme des microorganismes » 2018-2020, partenariat ECOBIO Rennes

Research staff involved

Research engineers, researchers and professors

  • ALOUINI Mehdi

    ALOUINI Mehdi

    (+33)2 23 23 66 58 Professor Directeur d’Unité

  • VALLET Marc

    VALLET Marc

    (+33)2 23 23 62 04 Professor Responsable d’équipe

PhD and post-doc

    Les anciens :

    • F. Parnet
    • A. Hallal
    • A. Rolland
    • …

To learn more…

  • Mehdi Alouini. Étude théorique et expérimentale des lasers solides Er3+ et Nd3+ : applications des lasers bi-fréquences aux télécommunications optiques et hyperfréquences. Optique [physics.optics]. Université de Rennes 1, 2001. Français. ⟨NNT : ⟩. ⟨tel-01850679⟩
  • Francois Bondu, Marc Brunel, Mehdi Alouini, Marc Vallet, Goulc’Hen Loas, et al.. DISPOSITIF DE PRODUCTION DE TRÈS HAUTES FRÉQUENCES PAR BATTEMENT DE FRÉQUENCES LUMINEUSES. France, N° de brevet: FR 2960354 / Texte intégral : http://bit.ly/1nOKVdW. 2012, pp.23. ⟨hal-00994792⟩
  • Gwennaël Danion, François Bondu, Goulc’Hen Loas, Ludovic Frein, Cyril Hamel, et al.. Synthèse optique d’ondes hyperfréquences et millimétriques à très bas bruit de phase : résultats préliminaires. Optique Bretagne 2015, Jul 2015, RENNES, France. , 2015. ⟨hal-01491862v2⟩
  • Ayman Hallal, Steve Bouhier, François Bondu. Synthesis of a 30-Hz Linewidth Wave Tunable Over 500 GHz. IEEE Transactions on Microwave Theory and Techniques, 2017, 65 (4), pp.1367-1371. ⟨10.1109/TMTT.2016.2635639⟩. ⟨hal-01427869⟩
  • Francois Bondu, Goulc’Hen Loas, Ludovic Frein, Cyril Hamel, Anthony Carré, et al.. An optical instrument for the submillimeter spectroscopy of the volatile metabolome. 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), Sep 2019, Paris, France. pp.19149312. ⟨hal-02292414⟩
Synthesis of RF and THz signals
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