  We describe a compact waveguide amplifier system that is suitable for
optically pumping rubidium magnetometers. The system consists of an
auto-locking vacuum-sealed external cavity diode laser, a semiconductor tapered
amplifier and a pulsing unit based on an acousto-optic modulator. The diode
laser utilises optical feedback from an interference filter to narrow the
linewidth of an inexpensive laser diode to ~500 kHz. This output is scannable
over an 8 GHz range (at 780 nm) and can be locked without human intervention to
any spectral marker in an expandable library of reference spectra, using the
autolocking controller. The tapered amplifier amplifies the output from 50 mW
up to 2 W with negligible distortions in the spectral quality. The system can
operate at visible and near infrared wavelengths with MHz repetition rates. We
demonstrate optical pumping of rubidium vapour with this system for
magnetometric applications. The magnetometer detects the differential
absorption of two orthogonally polarized components of a linearly polarized
probe laser following optical pumping by a circularly polarized pump laser. The
differential absorption signal is studied for a range of pulse lengths, pulse
amplitudes and DC magnetic fields. Our results suggest that this laser system
is suitable for optically pumping spin-exchange free magnetometers.
