Publications by authors named "Christoph S Werner"
Adiabatic frequency conversion has some key advantages over nonlinear frequency conversion. No threshold and no phase-matching conditions need to be fulfilled. Moreover, it exhibits a conversion efficiency of 100 % down to the single-photon level.
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- Lasing and self-pumped optical parametric oscillation are achieved in a micro-resonator made of neodymium-doped lithium niobate, with a laser output of 5 mW.
- At 6 mW output power, the combined signal and idler outputs exceed 1.2 mW, generating light wavelengths from 1.5 to 3.8 μm.
- This is the first demonstration of a quasi-phase-matched self-pumped nonlinear optical process in a micro-resonator, indicating potential for a cost-effective, wavelength-tunable coherent light source.
Optical microresonators attract strong interest because of exciting effects and applications ranging from sensing of single atoms and molecules to quantum and nonlinear optics. For all this, control and tuning of the discrete resonances are vital. In resonators made of anisotropic materials that are beneficial for nonlinear-optical applications, anticrossings of ordinarily (o) and extraordinarily (e) polarized modes occur regularly.
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- Ferroelectric domain walls are boundaries in materials where spontaneous polarization changes direction, leading to distinct properties.
- Recent research has achieved a significant breakthrough in lithium niobate, showing conductivity at charged domain walls that is over 13 times greater than the bulk material, with improved stability and accessibility.
- These advancements open up exciting possibilities for developing new optical components and advanced integrated devices for applications in quantum photonics.
Whispering-gallery resonators made of undoped and MgO-doped congruently grown lithium niobate are used to study electro-optic refractive index changes. Hereby, we focus on the volume photovoltaic and the pyroelectric effect, both providing an electric field driving the electro-optic effect. Our findings indicate that the light-induced photorefractive effect, combining the photovoltaic and electro-optic effect, is present only in the non-MgO-doped lithium niobate for exposure with light having wavelengths of up to 850 nm.
View Article and Find Full Text PDFWe achieve a continuous operation of a whispering gallery optical parametric oscillator by stabilizing the resonator temperature T on the mK level and simultaneously locking the pump frequency to a cavity resonance using the Pound-Drever-Hall technique. The millimeter-sized device converts several mW of a pump wave at 1040 nm wavelength to signal and idler waves around 2000 nm wavelength with more than 50% efficiency. Over 1 h, power and frequency of the signal wave vary by <±1% and by <±25 MHz, respectively.
View Article and Find Full Text PDFWe demonstrate a whispering gallery optical parametric oscillator pumped at 488 nm wavelength. This millimeter-sized device has a pump threshold of 160 μW. The signal field is tunable between 707 and 865 nm wavelength and the idler field between 1120 and 1575 nm through temperature variation.
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