arXiv subjects
Publications and source records attributed to Dirk-Mathys Spangenberg.
We extend the time-domain ptychographic iterative engine to generalized spectral phase-only transfer functions. The modified algorithm, i$^2$PIE, is described and its robustness is demonstrated by different numeric simulations. The concept is experimentally verified by reconstruction of a complex supercontinuum pulse from an all normal dispersion fiber.
We report the amplification of an all-normal dispersion supercontinuum pulse in a Thulium / Holmium co-doped all-fiber chirped pulse amplification system. With a -20 dB bandwidth of more than 300 nm in the range 1800-2100 nm the system delivers high quality 66 fs pulses with more than 70 kW peak power directly from the output fiber. The coherent seeding of the entire emission bandwidth of the doped fiber and the stability of the supercontinuum generation dynamics in the silicate glass all-normal dispersion photonic crystal fiber result in excellent noise characteristics of the amplified ultrashort pulses.
We demonstrate that time-domain ptychography, a recently introduced ultrafast pulse reconstruction modality, has properties ideally suited for the temporal characterization of complex light pulses with large time-bandwidth products as it achieves temporal resolution on the scale of a single optical cycle using long probe pulses, low sampling rates, and an extremely fast and robust algorithm. In comparison to existing techniques, ptychography minimizes the data to be recorded and processed, and drastically reduces the computational time of the reconstruction. Experimentally we measure the temporal waveform of an octave-spanning, 3.5~ps long supercontinuum pulse generated in photonic crystal fiber, resolving features as short as 5.7~fs with sub-fs resolution and 30~dB dynamic range using 100~fs probe pulses and similarly large delay steps.
An all optical implementation of pulse reconstruction using time-domain ptychography is demonstrated showing excellent results. Setup and reconstruction are easy to implement and a number of drawbacks found in other second order techniques are removed, such as the beam splitter modifying the pulse under consideration, the time ambiguity, or the strict correspondence between time delay increment and temporal resolution. Ptychography generally performs superior to algorithms based on general projections, requires considerable less computational effort and is much less susceptible to noise.