Engineering topics

Rubiola, Enrico

Publications and source records attributed to Rubiola, Enrico.

3 records

NASA NTRS2007

Raman-Suppressing Coupling for Optical Parametric Oscillator

A Raman-scattering-suppressing input/ output coupling scheme has been devised for a whispering-gallery-mode optical resonator that is used as a four-wave-mixing device to effect an all-optical parametric oscillator. Raman scattering is undesired in such a device because (1) it is a nonlinear process that competes with the desired nonlinear four-wave conversion process involved in optical parametric oscillation and (2) as such, it reduces the power of the desired oscillation and contributes to output noise. The essence of the present input/output coupling scheme is to reduce output loading of the desired resonator modes while increasing output loading of the undesired ones.

Savchenkov, Anatoliy↗

NASA NTRS2004

Phase-Noise and Amplitude-Noise Measurement of Low-Power Signals

Measuring the phase fluctuation between a pair of low-power microwave signals, the signals must be amplified before detection. In such cases the phase noise of the amplifier pair is the main cause of 1/f background noise of the instrument. this article proposes a scheme that makes amplification possible while rejecting the close in 1/f (flicker) noise of the two amplifiers. Noise rejection, which relies upon the understanding of the amplifier noise mechanism does not require averaging. Therefore, our scheme can also be the detector of a closed loop noise reduction system. the first prototype, compared to a traditional saturated mixer system under the same condition, show a 24 dB noise reduction of the 1/f region.

phase noise↗

NASA NTRS1990

Recent developments of Loran-C in Europe

Even if recent developments, both technical and political, are affecting the satellite Global Positioning System (GPS) and GLONASS navigation systems, alone, in conjunction, or with a possible civilian overlay via INMARSAT or other satellites, time has proven that Loran-C can still be a viable solution for many problems. The aims here are twofold, to present a panorama of the most recent developments in the world and mostly in Europe, and to consider some technical aspects of two problems regarding the Mediterranean Sea chain. This chain is based on four stations, two in Italy, one in Spain and one in Turkey. The fate of the station in Turkey is known, in the sense that this station will not operate when the U.S. support will cease; the future of the Spanish station is not yet known, while Italy has expressed its intention to operate the two remaining stations. Consequently two problems need to be solved to assure at least the coverage of Italy and of the eastern Mediterranean Sea.

Leschiutta, Sigfrido↗