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Communication Dans Un Congrès Année : 2009

Optoelectronic oscillator with an optical disk resonator

Résumé

Originally optoelectronic oscillators were built using optical delay lines. For example, the phase noise of 140 dBrad2=Hz at 10 kHz offset frequency can be achieved with km-size optical ber. Unfortunately the fiber suffers from curvature-dependent loss, which imposes liter-size spool. Recent advances in optical fiber technology decreased the size but it still remains of order of several centimetres. The use of optical resonators in optoelectronic oscillators is a logical step for achieving more compact assembly since they potentially allow achieve very high quality factors while the their sizes range from several millimeters to several micrometers. In this work we present our experiments concerning an optical disk resonator fabrication and preliminary results of its integration into an optoelectronic oscillator. Resonator material is MgF2. which is available as a highly pure crystal, harder than very popular CaF2 with its 6 Mohs hardness, and easier to manipulate without damaging the surface. It has the required optical and mechanical properties for building high Q resonator. We designed and built a machine for shaping and polishing small disk resonators. The resonator surface is ne-shaped and polished with Si powder and then with CeO2 powder of decreasing grain size, as it is usually done with optical surfaces. At the end of the process, local measurements show that rugosity is of 1-5 nm (3-12 atoms) rms. Unfortunately, the available instrument permits only the measurement of a small area, while a smooth defect-free surface is required in the whole equatorial region of the resonator. The first MgF2 resonator prototypes are disks of 5 mm diameter and 100 µm thickness, with spherically shaped edges. This geometry provides the free spectral range of about 15 GHz. The very first measured Q is of 3 x10 8. Though still modest compared to the record of 6 x10 10, it goes with some achievements, first of which a sharp and stable modal selectivity with 1µm tapered ber. Coupling with a tapered ber is still a critical step for integration and requires additional development. We have done a computer simulation of RF response of a photonic channel contain- ing a 1550 nm DFB laser, an electro-optical phase modulator, the miniresonator and a photodetector. First experimental results show workability of such architecture, with a potentially small size format.
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Dates et versions

hal-00384741 , version 1 (15-05-2009)

Identifiants

  • HAL Id : hal-00384741 , version 1

Citer

Hervé Tavernier, Kirill Volyanskyi, Ngan Nguyen Thi Kim, Patrice Féron, Laurent Larger, et al.. Optoelectronic oscillator with an optical disk resonator. IEEE Frequency Control Symposium & 23rd European Frequency and Time Forum, Apr 2009, Besançon, France. pp.P7245. ⟨hal-00384741⟩
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