We unambiguously determine the long-term frequency drift of a Brillouin-assisted self-linewidth-narrowing photonic oscillator, an original architecture that yields high spectral purity without any active stabilization, as we recently reported [ Opt. Express 33 , 1021 –1033 ( 2025 ) OPEXFF 1094-4087 10.1364/OE.534463 ]. A Pound–Drever–Hall locking scheme is used to compare the frequency of the free-running laser to a resonance frequency of a high-finesse Fabry–Perot cavity. The spectral purity of the optical wave, exhibiting a Flicker linewidth of 400 Hz for 0.1 s integration time, is shown to be preserved owing to a locking bandwidth of 5 Hz only. A smooth frequency drift bounded to 1 MHz over 7 h is revealed for the free-running laser. It demonstrates a stability of less than 10 −9 for 1000 s of integration time, outperforming the stabilities reported for free-running lasers.

We detail here the general principle of a self-adaptive oscillator in which the intertwined operation of a 100-m-long active optical resonator and a standard semiconductor laser mutually coupled by stimulated Brillouin scattering offers an ultimate high spectral purity. Single frequency operation of this self-adaptive photonic oscillator is achieved without any servo locking or stabilization electronics. In free running operation, this principle leads to a Lorentzian linewidth of 40 mHz and a Flicker noise linewidth of 200 Hz for 0.01 s integration time. The long-term drift of the optical frequency without absolute frequency locking is in the range of 10 MHz over hours. This principle applies to any wavelength attainable by laser diodes which opens tremendous opportunities, in particular in applications where atomic or molecular transitions require precise wavelengths.

We propose a theoretical description and experimental validation of a frequency self-stabilized photonic oscillator. This photonic oscillator which relies on a solid-state laser and a nonreciprocal Brillouin fiber resonator (BFR) arranged in an optical phase-locked loop (OPLL) was recently shown to provide very narrow linewidth in the Hz range. Special attention is given to end up with analytical expressions relying on coupled-mode formalism, of the BFR dynamics in which the non-resonant configuration for the pump has to be addressed. Furthermore, the transfer function of the full system is derived from the response of each component within the OPLL leading to two interleaved loops, relative to the phase and to the amplitude fluctuations of the optical field. An experimental setup including a solid-state Er:Yb laser is detailed and used to test the model predictions, both for phase noise level and response time. This model opens the way to the optimization of this new type of photonic oscillator which can be adapted to any kind of pump laser.

Highly coherent optical sources are a key element in several fields of physics, in particular in time frequency metrology. Over the past decennia, there has been particular efforts in developing such sources to the expense of sophisticated laser systems and relatively smart electronics. We propose here a new general principle of a self-adaptive oscillator where the intricate operation of a 100-m-long active optical resonator and a standard semiconductor laser offers a very high spectral purity and can be tailored to any wavelength. Single frequency operation of this self-adaptive photonic oscillator is achieved without any servo locking or stabilization electronics. Free running operation leads to a Lorentzian linewidth of 40 mHz. The long-term drift of the optical frequency in the free running regime is within 10 MHz over hours. This principle applies to any wavelength attainable by laser diodes which opens tremendous opportunities in particular in applications where atomic or molecular transitions require precise wavelengths.

We propose and demonstrate the possible self-narrowing of a laser line using optoelectronic and Brillouin approaches. Part of the laser is used to feed a long fiber Brillouin resonator whose Stokes wave is phase locked to the laser. The phase-locked loop which first forbids the multimode operation of the Brillouin resonator enables in a second time a dramatic reduction in the optical phase noise of the laser itself. In the case of a continuous Er,Yb:glass laser, a reduction by more than 90 dB at 100 Hz of the carrier is observed. This yields an optical linewidth reduction to 2 Hz. The method being independent of the laser wavelength, it can be implemented to almost any laser.

Stimulated Brillouin scattering (SBS) has received much attention for decades for its numerous applications in sensors, optical amplification or design of narrow-linewidth lasers. In particular, optical fibers present Brillouin gain with a narrow bandwidth of a few tens of MHz. This permits to realize Brillouin fiber lasers (BFL) emitting Stokes lines with potential ultra-narrow linewidths [1]. Standard architectures are based on the use of a long fiber loop in order to provide sufficient gain. The loop is then resonant for the pump requiring servo-control to lock the pump frequency to the loop resonance. Furthermore, the whole pump power may not be injected in the cavity, as the pump spectrum may be broader than the cavity resonance. Conversely, non-resonant pumping enables to fully exploit the pump power. However, as the pump-resonator detuning may drift, it suffers from mode-hopping of the Stokes wave.

We demonstrate that the implementation of phase-locked loop forbidding multimode operation of a long Brillouin resonator also leads to a dramatic reduction of the optical phase noise of the pump itself. In the case of a continuous Er,Yb:glass laser, a reduction by more than 90 dB at 100 Hz of the carrier is observed. This yields an optical linewidth estimated narrower than 2 Hz for the pump laser. The method being independent of the laser wavelength, it can be applied to almost any laser.

We report experimental evidence of the coupling between the pump diode current and the output differential phase in a two-axis two-polarization dual-frequency solid-state laser. The effect has the same transfer function shape as that for a pump current to output power one, suggesting a pump AM/laser PM coupling in the laser medium. We report that the pump amplitude noise is negligible in the laser differential phase noise assuming a linear coupling. (C) 2016 Optical Society of America

Nous presentons une nouvelle methode de stabilisation d’un laser Brillouin fibre de faible largeur de raie dont la pompe est non resonante pour la cavite fibree. Les sauts de mode sont supprimes au moyen d'une boucle a verrouillage de phase qui verrouille l’ecart en frequence entre l’onde de pompe et l’onde Stokes sur un oscillateur local RF. L‘oscillation monomode, a 1,55 µm, d’un laser Brillouin fibre de 110 m de long, est demontree pendant plusieurs heures, avec une largeur de raie optique inferieure 50 Hz. Le bruit de phase associe est egal a -60 dBc/Hz a 100 Hz avec une pente de -20 dB/decade.

We propose a reliable method for stabilizing narrow linewidth Brillouin fiber lasers with non-resonant pumping. Mode-hopping is suppressed by means of a phase-locked loop that locks the pump-Stokes detuning to a local radio-frequency (RF) oscillator. Stable single-mode operation of a 110-m-long Brillouin fiber laser oscillating at 1.55 μm is demonstrated for several hours. The beat note between two independent Stokes waves presents a phase noise level of -60  dBc/Hz at 100 Hz with a -20  dB/decade slope, and a FWHM linewidth lower than 50 Hz.

We report on optical components for integrated optics applications at the micro- and nanoscale. Versatile shapes and dimensions are achievable due to the liquid phase processability of SU8 resist. On the one hand, by adjusting the UV-lithography process, waveguiding structures are patterned and released from their original substrate. They can be replaced on any other substrate and also immerged in liquid wherein they still show off efficient light confinement. On the other hand, filled and hollow 1D-nanostructures are achievable by the wetting template method. By exploiting the large range of available SU8 viscosities, nanowires of diameter ranging between 50 nm and 240 nm, as well as nanotubes of controllable wall thickness are presented. Optical injection, propagation, and coupling in such nanostructures are relevant for highly integrated devices.

Nous avons concu et construit un systeme optique de synthese d’ondes hyperfrequences, millimetriques et submillimetriques a tres bas bruit de phase. Les resultats preliminaires montrent une densite spectrale de bruit de phase a 10 kHz de la porteuse d’une onde a 9 GHz limitee par l’appareil de mesure. Pour les bruits plus pres de la porteuse, le bruit de phase est limite par une modulation d’amplitude residuelle : le systeme est en cours de modifications.

Nous avons concu et construit un systeme optique de synthese d’ondes hyperfrequences, millimetriques et submillimetriques a tres bas bruit de phase. Les resultats preliminaires montrent une densite spectrale de bruit de phase a 10 kHz de la porteuse d’une onde a 9 GHz limitee par l’appareil de mesure. Pour les bruits plus pres de la porteuse, le bruit de phase est limite par une modulation d’amplitude residuelle : le systeme est en cours de modifications.

A beatnote, tunable from dc to 1 THz, provided by a dual-frequency laser is used to feed an unitravelling carrier photodiode in order to produce a highly coherent THz signal radiated by a transverse-electromagnetic-horn antenna. The THz signal is detected and analyzed by a subharmonic mixer coupled to an electrical spectrum analyzer. All components involved in this experiment operate at room temperature without phase locking the beatnote. So far, the dynamic range evolves from 58 dB at 282 GHz to 15 dB at 1.026 THz, and the measured linewidth is better than 30 kHz. Linewidth narrowing using a Brillouin fiber laser pumped by the dual-frequency laser leads to a beatnote of 500-Hz linewidth at 1 THz.

A dual-frequency 1.55 µm laser for CW low noise microwave, millimeter and sub millimeter wave synthesis is demonstrated, where frequency stabilization is possible on each wavelength independently.The solid state Er:Yb laser output power is 7 mW.The amplitude noise is -150 dBc/Hz at 1 MHz offset frequency.In free running regime, the frequency noise is 3.10 5 /f Hz/sqrt(Hz) (800 Hz on a 1µs timescale), better than commercial fibered or semi-conductor sources at this wavelength.

Le but de cette thèse est la synthèse optique d'ondes millimétriques et submillimétriques avec un très bas bruit de phase. La première partie concerne la réalisation d'un laser biaxe bifréquence dont chacune des deux fréquences est accordable indépendamment et continûment sur 1 THz. Ce laser est caractérisé en bruit d'amplitude et de phase. Nous avons mis en évidence un facteur de couplage entre les fluctuations de puissance de la diode de pompe et le bruit de phase du laser. La deuxième partie concerne le développement d'un système amplificateur qui se compose d'un amplificateur EDFA et d'un SOA par polarisation. Ce système amplificateur permet d'obtenir une puissance de l'ordre de 17 dBm, tout en réduisant le bruit relatif d'intensité (RIN) d'une vingtaine de dB sur 1 GHz. Cet amplificateur est également un actionneur pour la stabilisation de puissance permettant un RIN de l'ordre de -150 dB/Hz de 3 Hz à 5 kHz. La dernière partie concerne la mise en place du banc cavité et de l'asservissement des fréquences du laser sur une cavité ultra-stable. Nous obtenons un bruit de phase, à 10 kHz pour une porteuse à 10 GHz, meilleur que le plancher de bruit d'un analyseur de bruit de phase hautes performances de l'ordre de -115 dBc/ Hz. Le bruit de phase du système est indépendant de la fréquence de battement.

This Letter describes the design of an optical amplifier system optimized to reduce the relative intensity noise (RIN) of the input signal, and discloses its performance in terms of intensity noise reduction and bandwidth, without phase noise degradation. This polarization-maintaining amplifier is composed of an erbium-doped fiber amplifier (EDFA) cascaded with a semiconductor optical amplifier (SOA). The EDFA is sized to feed the SOA with a constant power corresponding to the optimal saturation level for noise reduction, through coherent population oscillations. When properly optimized, such an amplifier provides, simultaneously, 17 dB optical gain, 5.4 dB noise factor, and 20 dB reduction of the input-RIN across a 3 GHz bandwidth, without any electronics feedback loop.