Klaus Hartinger

Universal formation dynamics and noise of Kerr-frequency combs in microresonators

We experimentally investigate the initial dynamics of Kerr-frequency comb formation in crystalline MgF₂ and planar Si₃N₄ microresonator and present a universal, platform independent condition for low phase noise performance.

Dispersion engineering of thick high-Q silicon nitride ring-resonators via atomic layer deposition.

We demonstrate dispersion engineering of integrated silicon nitride based ring resonators through conformal coating with hafnium dioxide deposited on top of the structures via atomic layer deposition. Both, magnitude and bandwidth of anomalous dispersion can be significantly increased. The results are confirmed by high resolution frequency-comb-assisted-diode-laser spectroscopy and are in very good agreement with the simulated modification of the mode spectrum.

Dispersion balancing of variable-delay monolithic pulse splitters

We propose the use of birefringent materials to attain pulse separations suitable for pump-probe spectroscopy and spectral interferometry. By choice of material thickness and cut angle, it is possible to balance second-order dispersion while allowing for variable delays. The generated pulse pair is used to calibrate the phase response of an ultrafast liquid-crystal pulse shaper, and in the measurement of a rotational wave packet in impulsively aligned CO(2) molecules.

Single-shot measurement of ultrafast time-varying phase modulation induced by femtosecond laser pulses with arbitrary polarization

We demonstrate a single-shot measurement of the transient phase modulation due to field free molecular alignment at the revival times of a rotational wave packet. The wave packet is excited by an arbitrarily polarized ultrashort laser pulse in CO2 at room temperature. With this technique the time dependence along the eigenpolarization directions of the linear susceptibility tensor, i.e., the time dependence of its principle components, can be directly observed with high sensitivity.

Enhancement of third harmonic generation by a laser-induced plasma

We demonstrate more than two orders of magnitude in enhancement of conversion of an ultrafast probe pulse to the third harmonic that is time delayed with respect to a pump pulse. The enhancement is observed in various atomic and molecular gases over a range of pressures.

Microresonator-based optical frequency combs for high-bitrate WDM data transmission

A nonlinear high-Q SiN microresonator is used as a frequency comb generator for data transmission at 170.8 Gbit/s. The main sources for signal impairment are identified. Further dispersion engineering is crucial for Terabit/s transmission.

Universal dynamics of Kerr-frequency comb formation in microresonators

We experimentally investigate the initial dynamics of Kerr-frequency comb formation in crystalline MgF 2 and planar Si 3 N 4 microresonator and present a universal, platform independent condition for low phase noise performance.

Efficient nonlinear frequency conversion with a dynamically structured nonlinearity

A general technique for quasi phase matching of nonlinear frequency conversion in molecular gases through the dynamically structured nonlinear optical response of a molecular ensemble is presented. We show that the transient molecular alignment created by an ultrafast alignment pulse can be controlled to periodically modulate the strength of the nonlinear optical susceptibility in the reference frame of a fundamental pulse propagating through the aligned molecules. Simulations show efficient third harmonic generation of an ultrafast fundamental laser pulse.

Microresonator-based frequency comb generator as optical source for coherent WDM transmission

A high-Q SiN microresonator is used for the first time as an optical source for WDM transmission with advanced modulation formats. We transmit QPSK and 16QAM signals with a total bit rate of 392 Gbit/s.

Terabit/s data transmission using optical frequency combs

Terabit/s interconnects rely on advanced wavelength-division multiplexing (WDM) schemes. However, while efficient photonic-electronic interfaces can be efficiently realized on silicon-on-insulator chips, dense integration of WDM laser sources still represents a major challenge. Chip-scale frequency comb sources are an attractive alternative for providing optical carriers for WDM transmission. In this paper we give an overview on our recent work towards terabit/s data transmission using optical frequency combs. We demonstrate transmission of a 32.5 Tbit/s data stream using a modelocked solid-state laser as an optical source. Our current experiments aim at transmission schemes that exploit Kerr nonlinearities in high-Q microresonators for frequency comb generation.