Amplifier Seeding

High energy amplifiers have become a versatile and priceless tool in modern science, having enabled countless scientific breakthroughs deepening our knowledge about the inner workings of nature.

Todays femtosecond amplifiers mostly work by Chirped Pulse Amplification (CPA) (see Mourou et al. Opt. Com. Vol. 62, 1987) meaning that the pulse is first stretched to a duration in the picoseconds domain for more efficient amplification and then recompressed to a femtosecond pulse.

An often overlooked attribute is the temporal contrast of the resulting femtosecond pulse. One usually distinguishes between the ASE, pico-, nanosecond and pre-pulse contrast.

Recent works (Campbell et al., Applied Physics, 2004) have shown that some commercially available amplifier systems carry a lot of energy in their pico- and nanosecond pedestal (~25%) resulting in severe difficulties for the observation of real femtosecond effects. These have numerous causes and only careful design of the overall system enables the reduction of these artefacts to a mostly negligible level. Our amplifiers for example have a typical pico and nanosecond pedestal contrast of better than 1:10⁸ not easily found in other commercial systems.

However complex the exact nature of the pedestals may be an important starting point is a "clean" (in the time domain) oscillator pulse as a CPA system usually does not provide means to increase the main pulse / pedestal contrast. The oscillators manufactured by FEMTOLASERS satisfy this condition because of the very precise control available over the intracavity dispersion of the oscillator. Seeding an amplifier with one of our sources lays the founding stone for designing a system with good pedestal / main pulse contrast.

Due to the very special design of our amplifier system we have also succeeded in minimizing the main pulse / Amplified Spontaneous Emission (ASE) contrast to values typically better than 1:10⁹. This makes the FEMTOPOWER™ the ideal first stage seed amplifier for any amplifier chain with maximum contrast design goals (for example tera and petawatt systems).

The high bandwidth available to our systems (> 100 nm FWHM or even > 250 nm FWHM for the RAINBOW™ systems) enables the design of amplifiers supporting pulse durations shorter then 20 fs without the necessity of any active pulse shaping elements (Spielmann et al. Opt. Comm 2002). Using the RAINBOW™ system as a seed source you also have access to one of the most advanced CEP stabilised Ti:Sa systems on the market for inclusion into your amplifier system.

Of course our scientific seed oscillators accept a number of additions such as repetition rate control for synchronisation with an external source, pulse shapers etc. (please inquire for an exact list).

If you are searching for the ideal seed source for a non-scientific workstation we can offer you the INTEGRAL™, the first real turn key sub 20 fs (or even sub 10 fs) oscillator available. Its sophisticated integrated diagnostics systems and the 19" rack mountable power supply that can be easily connected to a computer via the RS232 interface make it ideal for inclusion into systems designed for the most demanding customers. You now have all the advanced attributes of our seed sources available to you at the push of a button.

Custom solutions are of course always available on request (like custom wavelength region, custom bandwidth, custom repetition rate etc., please inquire for details).