Page 15 - Visions of the Future Chemistry and Life Science

Figure 1.2. Photograph of a Tsunami titanium:sapphire laser manufactured by Spectra-Physics Lasers Inc.
(Mountain View, California). The lasing transition in Ti:sapphire is between vibrational levels of different
electronic states of the Ti 3 ion. Mode-locking of the laser is induced by an acousto-optic modulator,
which results in the propagation of pulses with high peak powers and femtosecond durations in a single,
‘locked’ mode, or standing wave pattern. The energy source required to drive a Ti:sapphire laser is
provided either by a diode or an argon-ion laser, both of which lase at the green wavelengths where Ti 3 is
strongly absorbing. When the population of the Ti 3 excited state exceeds that of the ground state, laser
radiation is emitted at red and near infrared wavelengths between 670 and 1070 nm.