Facilities



 


a. Carrier-envelope phase (CEP) stabilized Titanium: Sapphire ultrafast laser amplifier

Customized FEMTOPOWER compact PRO amplifier from Femtolasers GmbH. This system has dual CEP stabilized outputs, delivering: i) 2.5 nJ pulses with sub-7-fs duration at a repetition rate of 80 MHz (from the included Femtolasers Rainbow CEP laser oscillator); ii) up to 1 mJ pulses with sub-30-fs duration at a repetition rate of 1 kHz. This system is a key tool for advanced (high-resolution and CEP-dependent) ultrafast science, including ultrafast nonlinear optics, ultrafast laser-matter interaction and ultrafast pump-probe spectroscopy experiments.



b. Home-built Titanium:Sapphire ultrafast laser oscillator

This was the first few-cycle femtosecond laser in Portugal (built in 2000). It delivers 10 fs pulses at a repetition rate of 80 MHz and a central wavelength of 800 nm, with an average power of up to 600 mW. These pulses can be used in a variety of experiments, from nonlinear excitation and propagation to pump-probe studies. The emitted laser pulses can also be tuned over a broad spectral range (700-900 nm). By propagating the pulses in a short piece of photonics crystal fiber this system enables the generation of ultra-broadband coherent spectra (also known as super continua) spanning over the ultraviolet, visible and near-infrared regions, which has also enabled producing the shortest soliton-compressed pulses in the world (sub-5-fs).


 

c. Home-built hollow-fiber compressor for few-cycle pulse generation

This system takes advantage of the nonlinear propagation of amplified laser pulses in noble gas-filled hollow capillaries to produce unprecedentedly short laser pulses. Using a proprietary measurement and compression scheme (dispersion-scan) based on a set of ultra-broadband dispersion compensation mirrors, we have achieved the shortest pulses ever obtained from a single-channel pulse compressor: 3.0 fs. These pulses are already in the single-cycle regime and enable the direct observation of field-dependent phenomena in many materials.



d. Dispersion-scan system (d-scan)

Dispersion-scan (d-scan) is an innovative technique (patent pending) for the simultaneous measurement and compression of ultrashort laser pulses. D-scan (invented in our group, in collaboration with Lund University in Sweden) is more robust, much easier to implement and more performing than other conventional pulse measurement techniques. Our in-house design includes automated measurement/acquisition and pulse retrieval.


 

e. Sub-30-fs deep-ultraviolet pulse source at 266 nm

Ultrashort UV light is generated by non degenerate four-wave mixing of femtosecond pulses at 800 nm and their second-harmonic at 400 nm. These pulses can be used to directly excite and probe energetic levels in atoms and molecules at femtosecond time scales.

Contact person: hcrespo@fc.up.pt