The basic idea behind the d-scan technique for measuring the duration of ultrashort laser pulses is to record the pulse’s second harmonic spectrum, generated in a suited nonlinear material (or exploit another nonlinear interaction), while the dispersion of the pulse, i.e. the spectral phase, is manipulated. From a recorded d-scan trace, i.e. second harmonic spectrum vs. dispersion, the spectral phase of the pulse can be retrieved with different computer based methods. Knowledge of the spectrum (measured separately or retrieved) and of the spectral phase (result of the retrieval) give the pulse in the time domain by Fourier transform operations. Even without retrieval, the d-scan trace itself is intuitive to interpret, as basic pulse distortions manifest as shifts, tilts or bends of the trace, therefore giving immediate, intuitive feedback to the laser operator.
The main goal of the project is to lift the technology readiness levels of different single-shot d-scan implementations, in particular concerning different wavelengths ranges relevant to different laser technologies and applications as well as the range of measurable pulse durations. Towards the end of the project, products will exist covering relevant ranges of pulse duration for scientific as well as industrial and medical applications. Up to this moment, all hurdles on this pathway, as initially outlined in the research proposal, have been taken.
In particular, the following intermediate goals have been achieved:
- An experimental setup to measure the dispersion of optical materials, in particular transverse second harmonic generation (TSHG) crystals, was realized (D2.1)”
- Designs for chirped mirrors at the important wavelengths of 800 nm and 1030 nm were established (D2.3).
- The working principle of the d-shot at 1030 nm was demonstrated as proof-of-concept (M1).
