Ultra-fast opto-electronic switching device with high isolation power and wide passband, comprises semiconductor substrate with dielectric layer and modified photoconduction zone

摘要

The optoelectronic switching device comprises two conductor elements (11,12) separated by a gap (13), a dielectric layer (31) of low relative permittivity, a semiconductor substrate layer, and means for illuminating the gap part on a photoconduction zone (16) for modifying the conductivity of the substrate in the zone so to make it locally conducting. The dielectric layer (31) is interrupted above the photoconduction zone and replaced by an air layer (34) allowing to isolate the conductor elements from the substrate in the illumination zone. The air layer (34) is transparent for the optical signal and allows the illumination of the substrate without reflection. The substrate thickness at the level of the photoconduction zone is reduced in order to decrease the stray capacitance linked to the substrate. The reduction of the substrate thickness is implemented on the upper face of the substrate by freed space forming another air layer (36), or on the lower face of the substrate so that the substrate thickness in the conduction zone is substantially equal to the absorption thickness of the substrate for the wavelength corresponding to the illumination. The illumination of the substrate is by an optical signal from a source such as an optical fibre directly illuminating the substrate, or by an optical signal carried by an optical waveguide placed on the upper face of the circuit, or an optical waveguide integrated in the substrate at a depth substantially equal to the absorption thickness, on the upper face or the lower face of the substrate. The optical waveguide distributes the optical signal to several devices. Applications (claimed) of the device (claimed) include the ultrafast sampling of super-high frequency signals propagating in the conducting line, the control of gain of amplifiers, the implementation of phase-shifting circuits, and the implementation of oscillator circuits controlled in frequency.