High-resolution microwave frequency dissemination on an 86-km urban optical link

We report the first demonstration of a long-distance ultra stable frequency dissemination in the microwave range. A 9.15 GHz signal is transferred through a 86-km urban optical link with a fractional frequency stability of 1.3x10-15 at 1 s integration time and below 10-18 at one day. The optical link phase noise compensation is performed with a round-trip method. To achieve such a result we implement light polarisation scrambling and dispersion compensation. This link outperforms all the previous radiofrequency links and compares well with recently demonstrated full optical links.Comment: 11 pages, 5 figure

RED glass-based microcavities enabling luminescence control

International audienceOptical microcavities are structures that enable confinement of light to microscale volumes. Moreover, depending on their geometrical, compositional and structural parameters such sub-wavelenght photonic systems allow a fine tailoring of the luminescence, when activated by luminescent species. Here we focus our attention on 1-D photonic crystals and on spherical microresonators, both of them activated by Er3+ ions. The glass-derived 1-D photonic crystal is a microcavity constituted by an erbium-doped layer sandwiched between two Bragg mirrors respecting a lambda/2 periodicity, where lambda is the desired operating resonance wavelength. This microcavity is fabricated by rf-sputtering. The spherical microresonator consists in a silica sphere with a diameter of about 150 µm coated with a erbium-doped silica-hafnia layer of about 1 µm in thickness. The spherical substrate is obtained by melting a fiber and the coating is achieved by sol gel dip-coating technique. The 1-D microcavities exhibits a significant quality factor The effect of the cavity on the 4I13/2→4I15/2 emission band is demonstrated by the narrowing of the emission band as well as by the enhancement of the Er3+ photoluminescence intensity.The Er3+ 4I13/2→4I15/2 luminescence, excited by the whispering gallery modes typical of these cavities, exhibits interesting properties as a function of the geometrical properties of the resonator

Областная газета. 2006. № 282/283. Ветеран Среднего Урала

Abstract—The photodiode impact on the phase noise of an optical link, and particularly its ability to convert the laser amplitude noise into microwave phase noise, is studied and modeled. The model involves a nonlinear RC cell which describes a photogeneration delay which is a function of the optical power. The whole system is then implemented on a microwave CAD software, and the link gain and phase noise performance are computed. Keywords—photodiode; nonlinear modelling; CAD; microwave-optics; phase noise; optical fiber link I

Low frequency noise characterization and modeling of microwave bipolar devices : application to the design of low phase noise oscillator

This paper addresses advanced low frequency noise measurements and modeling of SiGe HBTs. Results have been implemented into a nonlinear Gummel Poon model which has been validated through the design of a DRO made of an integrated SiGe negative resistance in the 10 GHz range. We have obtained phase noise of -105 dBc/Hz at 10 kHz offset, which is close to the state of the art, and we have demonstrated a design technique that provides an accurate phase noise prediction

Tailoring of the free spectral range and geometrical cavity dispersion of a microsphere by a coating layer

International audienceThe modal dispersion of a whispering gallery mode (WGM) resonator is a very important parameter for use in all nonlinear optics applications. In order to tailor the WGM modal dispersion of a microsphere, we have coated a silica microsphere with a high-refractive-index coating in order to study its effect on the WGM modal dispersion. We used Er3+ ions as a probe for a modal dispersion assessment. We found that, by varying the coating thickness, the geometrical cavity dispersion can be used to shift overall modal dispersion in a very wide range in both the normal and anomalous dispersion regime

Low frequency noise characterization and modeling of microwave bipolar devices: Application to the design of low phase noise oscillator

This paper addresses advanced low frequency noise measurements and modeling of SiGe HBTs. Results have been implemented into a non linear Gummel Poon model which has been validated through the design of a DRO made of an integrated SiGe negative resistance in the 10 GHz range. We have obtained phase noise of -105 dBc/Hz at 10 kHz offset, which is close to the state of the art, and we have demonstrated a design technique that provides an accurate phase noise prediction