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Room-temperature, continuous-wave laser action at 2.3 microm corresponding to the (3)H(4)-(3)H(5) transition in Tm(3+)- doped YLF is achieved. Output powers of 200 mW and a slope efficiency of 15% have been obtained for a pump power of 2 W at 0.78 microm. In addition, continuous tunability of this laser from 2.20 to 2.46 microm is obtained.

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Continuous-wave mode-locked operation of a 2-microm Tm: YAG laser is demonstrated. Stable, transform-limited pulses of 35-ps duration have been generated at a repetition rate of 300 MHz, with an average output power of 70 mW.

Spectrally resolved emission (270-560 nm) from dilute suspensions of washed Bacillus subtilis and Escherichia coli were measured by use of tunable laser excitation between 270 and 300 nm. Integrated absolute emission cross sections increase with decreasing excitation wavelength and range from 1.8 x 10(-12) to 6.0 x 10(-11) cm(2)/(particle sr). An emission band near 340 nm dominates all observed spectra. At each excitation wavelength spectrally resolved emissions from the E. coli and B. subtilis suspensions are indistinguishable.