Seeded optical amplifier apparatus for producing Femtosecond pulses
A source of femtosecond optical pulses comprises a seed pulse source arranged to generate seed pulses; an optical amplifier downstream of the seed pulse source, the optical amplifier having a gain bandwidth; a nonlinear optical element downstream of the amplifier, the optical element spectrally broadening optical pulses via a non linear process to have a spectral bandwidth that exceeds the gain bandwidth of the optical amplifier; and a pulse compressor downstream of the nonlinear optical element and arranged to reduce the temporal duration of optical pulses so as to provide output optical pulses having a femtoseconds time duration.
1. A source of femtosecond optical pulses, comprising:
a seed pulse source arranged to generate seed pulses;
an optical amplifier downstream of the seed pulse source, the optical amplifier having a gain bandwidth;
a nonlinear optical element downstream of the optical amplifier, the nonlinear optical element spectrally broadening optical pulses via a nonlinear process to have a spectral bandwidth that exceeds the gain bandwidth of the optical amplifier; and
a pulse compressor downstream of the nonlinear optical element and arranged to reduce the temporal duration of optical pulses so as to provide output optical pulses having a femtoseconds time duration.
2. The source of femtosecond optical pulses of claim 1 wherein the seed pulse source generates optical pulses having a time duration of greater than 1 picosecond.
3. The source of femtosecond optical pulses of claim 1 wherein said nonlinear optical element comprises an optical fibre.
4. The source of femtosecond optical pulses of claim 3 wherein said optical fibre comprises a passive optical fibre.
5. The source of femtosecond optical pulse of claim 3 wherein said optical fibre comprises a ytterbium doped optical fibre.
6. The source of femtosecond optical pulses of claim 1 wherein said pulse compressor comprises a fibre Bragg grating.
7. The source of femtosecond optical pulses of claim 1 wherein said pulse compressor comprises a bulk grating pair.
8. A method of generating femtoseconds output optical pulses from input optical pulses, comprising:
amplifying the optical seed pulses provided by a seed pulse source, the amplification process having a gain bandwidth;
spectrally broadening optical pulses, downstream of the amplification, using a non-linear process to provide optical pulses having a spectral bandwidth that exceeds the gain bandwidth; and
compressing optical pulses, downstream of the spectral broadening, so as to produce the output optical pulses having a femtoseconds time duration.
9. The method of claim 8 wherein the optical seed pulses have a time duration of greater than 1 picosecond.
10. The method of claim 8 wherein spectrally broadening comprises spectrally broadening using an optical fibre.
11. The method of claim 10 wherein the fibre comprises a ytterbium doped optical fibre.
12. The method of claim 10 wherein the fibre comprises a passive optical fibre.
13. The method of claim 8 wherein compressing comprises compressing optical pulses using a fibre Bragg grating.
14. The method of claim 8 wherein compressing comprises compressing optical pulses using a bulk grating pair.