Multicolor diode-pumped upconversion fiber laser.

We present a new method to control the power of individual spectral components of a multicolor laser by mirrors with variable air gaps and by a composite resonator configuration. We demonstrate a Pr/Yb-ZBLAN fiber laser with arbitrary spectral composition of three simultaneously emitted components at 492 nm, 520 nm, and 635 nm. With 100 mW pump power at 850 nm launched into the fiber, the total laser output exceeds 10 mW.

External photoacoustic detection of a trace vapor inside a multimode laser.

We combine highly sensitive intracavity absorption spectroscopy in a multimode laser with external photoacoustic detection, providing high detectivity. Photoacoustic measurements of the intracavity iodine concentration in a Rhodamine 6G laser are compared with simultaneous spectral recordings. They demonstrate slightly improved overall sensitivity and a greatly enhanced dynamic range of 5 orders of magnitude that may be shifted along the absolute scale of absorber density.

Intracavity absorption spectroscopy with a Nd(3+)-doped fiber laser.

A broadband Nd(3+)-doped fiber laser has been operated in an external cavity by pumping with an Ar(+)-ion laser. The emission spectrum of the fiber laser shows high sensitivity to intracavity absorption. The equivalent absorber path length is 15 km; with a loss-reduced setup that includes pumping by a diode laser this path length is 150 km.