Viktor Quiring

Integrated Optical Devices in Lithium Niobate

Lithium niobate offers incredible versatility as a substrate for integrated optics. Researchers have developed an array of new optical devices based on this material, including waveguide structures, electro-optical wavelength filters and polarization controllers, lasers with remarkable properties, nonlinear frequency converters of exceptional efficiency, ultrafast all-optical signal processing devices and single photon sources.

Distributed feedback-distributed Bragg reflector coupled cavity laser with a Ti:(Fe:)Er:LiNbO3 waveguide

A thermally fixed photorefractive Bragg grating is written in a single-mode Ti:Fe:Er:LiNbO3 channel waveguide and used to develop a distributed feedback-distributed Bragg reflector coupled cavity laser with a second broadband dielectric cavity mirror. The optically pumped (lambda(p) = 1480 nm, P = 130 mW) laser emits in single-frequency operation as much as 8 mW at lambda = 1557.2 nm with a slope efficiency of approximately 22%. The laser wavelength can be thermo-optically and electro-optically tuned over 100 pm.

Nonlinear integrated optical frequency converters with periodically poled Ti:LiNbO3 waveguides

The development of a whole family of near and mid-IR quasi- phase matched parametric frequency converters with periodically poled in Ti:(Er:)LiNbO3 waveguides is reviewed. Due to high quality waveguides with very low losses and excellent homogeneity unprecedented conversion efficiencies have been achieved for second-harmonic generation, difference-frequency generation, optical parametric fluorescence and doubly as well as singly resonant optical parametric oscillation.

Wavelength- and time-selective all-optical channel dropping in periodically poled Ti:LiNbO 3 channel waveguides

Wavelength- and time-selective channel dropping by sum frequency generation of a 10-GHz channel out of a 4 /spl times/ 10 GHz optical time-division-multiplexed signal has been demonstrated using two fully packaged Ti : PPLN wavelength converters. Less than -15 dB of channel dropping extinction ratio is observed with average (peak) coupled pump power of 100 mW (2 W).

Demonstration of coherent time-frequency Schmidt mode selection using dispersion-engineered frequency conversion

Time-frequency Schmidt (TFS) modes of ultrafast quantum states are naturally compatible with high bit-rate integrated quantum communication networks. Thus they offer an attractive alternative for the realization of high dimensional quantum optics. Here, we present a quantum pulse gate based on dispersion-engineered ultrafast frequency conversion in a nonlinear optical waveguide, which is a key element for harnessing the potential of TFS modes. We experimentally retrieve the modal spectral-temporal structure of our device and demonstrate a single-mode operation fidelity of 80\%, which is limited by experimental shortcomings. In addition, we retrieve a conversion efficiency of 87.7\% with a high signal-to-noise ratio of 8.8 when operating the quantum pulse gate at the single-photon level.

10-GHz clock recovery using an optoelectronic phase-locked loop based on three-wave mixing in periodically poled lithium niobate

Clock recovery is a critical function of any digital communications system. To replace the classical electronic phase-locked loops (PLLs) at higher bit rates, several all-optical or optoelectronic clock recovery methods are being studied. This letter presents an optoelectronic PLL where three-wave mixing in a periodically poled lithium niobate (PPLN) device provides the phase comparator. Since PPLN is passive, it generates no amplified spontaneous emission noise; also, the error signal is in the visible (763 nm), therefore easily separated from infrared input signals. Clock recovery is performed on a 10-GHz sinusoidal optical signal. Being based on ultrafast nonlinear effects, this scheme should be able to reach still higher bit rates, on the order of several hundred gigahertz. Also, subclock extraction (e.g., 40-to-10 GHz) should be possible without modifications.

Field demonstration of in-line all-optical wavelength conversion in a WDM dispersion managed 40-Gbit/s link

The development of wavelength-division multiplexing (WDM) all-optical transport networks is an interesting solution to increase the capacity of long-haul transmission systems and to solve the route-exhaust problems of metropolitan networks, driving down the cost of that traffic. Routing can be achieved using a transparent device able to select and interchange wavelengths, such as an all-optical wavelength converter. In this paper, an optical transport network over an embedded link located between Rome and Pomezia in Italy is emulated. The transmission has been realized along a WDM, 5/spl times/100 km long, dispersion managed link at 40 Gb/s. The in-line rerouting process has been controlled by means of an all-optical wavelength converter realized with a periodically poled lithium niobate waveguide. Moreover, a polarization-independent scheme for the converter has been exploited to allow the in-line signal processing. This scheme is based on the counterpropagation of TE and TM signal components along the same guide and results extremely compact. In this paper it is demonstrated that wavelength conversion and rerouting add no penalty with respect to the simple transmission along the embedded cable. This result seems to be another step toward the feasibility of true all-optical networks.

Direct generation of genuine single-longitudinal-mode narrowband photon pairs

The practical prospect of quantum communication and information processing relies on sophisticated single photon pairs which feature controllable waveform, narrow spectrum, excellent purity, fiber compatibility and miniaturized design. For practical realizations, stable, miniaturized, low-cost devices are required. Sources with one or some of above performances have been demonstrated already, but it is quite challenging to have a source with all of the described characteristics simultaneously. Here we report on an integrated single-longitudinal-mode non-degenerate narrowband photon pair source, which exhibits all requirements needed for quantum applications. The device is composed of a periodically poled Ti-indiffused lithium niobate waveguide with high reflective dielectric mirror coatings deposited on the waveguide end-faces. Photon pairs with wavelengths around 890 nm and 1320 nm are generated via type II phase-matched parametric down-conversion. Clustering in this dispersive cavity restricts the whole conversion spectrum to one single-longitudinal-mode in a single cluster yielding a narrow bandwidth of only 60 MHz. The high conversion efficiency in the waveguide, together with the spectral clustering in the doubly resonant waveguide, leads to a high brightness of

Highly efficient frequency conversion with bandwidth compression of quantum light

3\times10^4~

Microresonator-enhanced electroluminescence of an organic light emitting diode based on a columnar liquid crystal

pairs/(s