Optical Waveguide Cross-Correlator for Attosecond Timing Synchronization

This Phase II STTR will develop a precision balanced optical cross-correlator using engineered nonlinearoptical waveguides. The proposed device will be important for future advances at large scale accelerator facilities by providing a means to achieve long-term sub-femtosecond timing and synchronization of all of a facilitys optical and RF sub-systems over fiber optic links. Statement of how this problem or situation is being addressed. The innovative
balanced optical cross-correlation technique takes advantage of a wide bandwidth second harmonic generation (SHG) interaction that is possible in periodically-poled KTP (PPKTP) crystals to measure the arrival time difference between two optical pulses while cancelling errors due to intensity fluctuations and photodetector phase noise. A waveguide-based cross-correlator offers substantial improvements compared to bulk PPKTP through orders of magnitude better SHG efficiency and compact, robust, noisefree, fiber-coupled packaging.
Results of Phase I. The Phase I STTR effort firmly established the feasibility of using KTP waveguides in a balanced optical cross-correlator, providing evidence that these devices will provide substantial improvement in sensitivity compared to their bulk-opticdevicecounterparts, in addition to being smaller, cheaper, and more robust. Waveguidecomponents were modeled, designed, and tested to verify that they can support a coupling scheme for combining wavelengths from fiber inputs directly in the waveguides and the direct integration of photodetectors with waveguides was demonstrated.
The proposed Phase II effort. The Phase II objectives are to fabricate KTP waveguides with integrated directional couplers and high conversion efficiency and wide bandwidth SHG, package KTP waveguide-based cross-correlators incorporating integrated detectors and fiber optical inputs, and test the integrated fiber-coupled packaged device and its
environmental sensitivity and demonstrate its usefulness in a ttosecond precision pulsed optical timing distribution system. Commercial applications and other benefits. A robust, fiber-based device will improve and simplify precision timing at linear accelerators, improving performance and reducing maintenance and installation costs. Future advances in basic science research, radar and telecommunications, quantum communication, and quantum computation will also depend upon precision timing at attosecond time scales.