Doubly resonant Ti:sapphire laser

A CW Ti:sapphire laser that operates simultaneously at two frequencies is described. This mode of operation was obtained with an intracavity dispersive prism and two separate feedback paths. An alternative means of achieving dual frequency operation was demonstrated using a birefringent filter. Repetitive Q-switching produced an increase in the range of wavelengths over which dual frequency operation was obtained     

Laser-diode-pumped Cr:LiSrGaF6 laser

Diode-pumped operation of a Cr:LiSrGaF₆ laser is described. Efficient performance was obtained between 810 and 855 nm. The maximum output power was 130 mW at 810 nm, and the slope efficiency was 26%. The sample was pumped with a total incident power of 560 mW using two polarization-combined high-power visible laser diodes. These results represent the CW power reported for a diode-pumped Cr-doped laser     

Low-threshold dye laser pumped by visible laser diodes

The author describes a continuous-wave (CW) dye laser has been pumped by laser diodes for the first time. Two 10-mW visible laser diodes were polarization-combined to pump a rhodamine 700 dye jet laser. The absorbed pump threshold power was 5.6 mW, and 0.28 mW of output power was produced at 758 nm. The resonator was scalable and generated over 360 mW with a slope efficiency of 57% when pumped with a DCM dye laser at 660 nm     

Efficient, scalable, internally folded Nd:YAG laser end-pumped bylaser diodes

A scalable diode-pumped Nd:YAG laser is described in which the gain element resembles a penta-prism. This design allows longitudinal pumping along five separate axes. Using five high-power single stripe laser diodes, 4.16 W of absorbed power produced 2.3 W CW at 1.06 μm. The slope efficiency was 56%, the output was plane polarized, and the laser operated in the TEM₀₀ mode. The threshold power, was 48 mW. No evidence of thermal saturation was observed up to the maximum pump power. With an intracavity KTP crystal, 431 mW of CW amplitude-stable output at 532 nm was generated. Repetitive Q-switched operation is also reported     

Er3+:YAlO3 upconversion laser

Upconversion lasing in Er:YAlO₃ is reported. Laser emission was produced using both sequential two-step pumping and cross-relaxation energy transfer. In addition, photon avalanche upconversion pumping was demonstrated. Selection among these pumping mechanisms is determined by the pump wavelength, and laser operation was obtained with excitation between 785 nm and 840 nm. The highest laser output power was achieved at 34°K, where 918 mW of pump power at 807 nm produced 121 mW of TEM₀₀ emission. The optical conversion efficiency was 13%. Repetitively Q-switched operation is reported, and the temporal- and temperature-dependence of the laser output is discussed     

Production of 1‐Octanol from n‐Octane by Pseudomonas putida KT2440

A two‐phase biotransformation process for selective hydroxylation of n‐octane to 1‐octanol via Pseudomonas putida KT2440 harboring heterologously expressed P450 monooxygenase from Mycobacterium marinum is presented. Maximum cell‐specific conversion rates of 12.7 mg_octanol g_CDWh^–1 were observed not only in shaking flasks but also in 3.7‐L‐bioreactor studies. The bioreactor experiments were performed avoiding explosive gas mixtures by lowering volumetric power input, aeration rates and substrate concentrations. Based on a stoichiometric network of P. putida KT2440 topological studies were carried out. As a conclusion, potential limitations of NAD(P)H and/or ATP supply at production conditions can be excluded. Hence, the great potential of the host for further increasing conversion is outlined.     

High-efficiency 1.06-µm output in a monolithic Nd:YVO(4) laser

A miniature 1.5-mm-long monolithic Nd:YVO(4) laser was end pumped with a Ti-sapphire laser. The Nd-doping density was 3 at. %. The maximum output power obtained with 885 mW of absorbed pump power was 495 mW at 1.064 μm. The maximum slope efficiency was 57%, and the output power was only slightly dependent on pump polarization. Laser diode pumping was also demonstrated. Thermal effects were observed to reduce the output power and required active cooling of the laser crystal.     

A single frequency Nd:YAG ring laser pumped by laser diodes

The design and operation of a diode-pumped Nd:YAG ring laser is described. The laser is shown to be a highly versatile device, capable of efficient generation of both the fundamental and second harmonic frequencies, CW and Q-switched. Single-frequency outputs in excess of 540 mW at 1.06 μm and 18.9 mW at 532 nm output were obtained, whereas multi-longitudinal mode Q-switched operation produced 22.4 μJ per pulse at 5 kHz in the fundamental and 7.3 μJ power pulse at 532 nm     

Near-IR dye laser for diode-pumped operation

A dye laser pumped by AlGaInP laser diodes produced efficient, low threshold operation at wavelengths between 740 and 800 nm. Rhodamine 700, oxazine 750, DOTCI and oxazine 1 dyes were demonstrated. Optical conversion efficiencies approaching 50% and output power as high as 361 mW were obtained when pumping with a DCM-based dye laser. Parametric variations of the pump power and wavelength were performed over the range of 615 nm to 690 nm to provide a more complete characterization of the dye laser     

End-pumped Yb-doped fluorapatite laser

An ytterbium:fluorapatite (Yb:FAP) laser crystal was longitudinally pumped using a Ti:sapphire laser emitting at 905 nm. The highest slope efficiency obtained was 60.5%, and the maximum output power was 214 mW with a pump power of 438 mW. Repetitive Q-switching was demonstrated for the first time. The Q-switched average power was identical to the continuous-wave (CW) power at repetition rates exceeding 20 kHz, as is consistent with the 1.08-ns emission lifetime