Page 335 - High Power Laser Handbook

304 So l i d - S t at e La s e r s Ultrafast Solid-State Lasers 305

Center Pulse Pump Typical
Material Wavelength Duration Laser Average Power
Ti:sapphire 800 nm < 10 fs Nd:YVO, 100–2000 mW
532 nm
Yb:KGW/KYW 1050 nm < 200 fs Diodes, 1–3 W
980 nm
Yb:YAG 1030 nm < 200 fs Diodes, 1–10 W
940 nm
Cr:LiSAF 840 nm < 50 fs Diodes, 100 mW
670 nm
Cr:Forsterite 1235 nm < 100 fs Nd:YAG, 100 mW
1064 nm
Cr:ZnSe 2500 nm < 100 fs Tm:Fiber, 50–100 mW
1900 nm
Er:Fiber 1550 nm < 50 fs Diodes, 50 mW
940 nm
Yb:Fiber 1030 nm < 200 fs Diodes, 100–1000 mW
980 nm

Table 12.1 Sample of Femtosecond Sources (List is Not Meant to be
Comprehensive.)

lasers (OPSLs) have been introduced as a new source for pumping
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Ti:sapphire. In addition, frequency-doubled fiber lasers are an
attractive low-cost alternative to Nd:YVO systems. 15

12.3 Ultrafast Amplification Techniques

Ultrafast laser systems suffer from complexity due to their high peak
power nature. To bring lower-energy nanojoule pulses up to milli-
joule pulses or higher, the pulse being amplified must increase in
duration to avoid high peak powers (Power = Energy/Duration) in
the amplifier chain to avoid causing damage. In 1985, the idea of
chirped pulse amplification (CPA) was introduced as a method for
16
bringing low-energy, ultrafast pulses to energies of less than 1 J. The
broad-bandwidth nature of ultrafast pulses can also be challenging.
Because bandwidths can be rather large (oscillators can span more
than an octave), managing all the different frequencies can be diffi-
cult. Care must be taken when choosing ultrafast components, such
as waveplates, polarizers, Brewster windows, and anything that has
a frequency-dependent result. In particular, strongly dispersive ele-
ments, such as gratings and prisms, have a propensity to introduce
aberrations by coupling the spatial and spectral content of the beams.