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Single frequency operation of a diode-pumped tunable injection-seeded Nd:GSAG Q-switched laser around 942nm was demonstrated. With a three-mirror ring cavity, the single frequency laser pulse with output energy of 13.2mJ was obtained at a repetition rate of 10Hz. The linewidth of the single frequency laser was less than 100MHz. The wavelength of the single frequency Nd:GSAG laser can be tuned from 942.38nm to 943.10nm.

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A Nd:GSAG laser operated at the 4 F 3/2 → 4 I 9/2 transition was tuned by a FPI-etalon achieving a tuning range of 1.5 nm with a center wavelength at 942.7 nm. Three water vapor absorption wavelengths with different absorption strength as suitable for a water vapor LIDAR are within this tuning range and lasing could be achieved at all three wavelength. Q-switched pulse energies up to 26 mJ were obtained as required for long range detection.

The wavelength-dependent Jones matrix representation of a twisted-nematic liquid crystal (TN-LC) cell contains four independent parameters. The absolute values of these parameters and two mutual sign relationships can be determined from comparatively simple transmission measurements of the TN-LC cells sandwiched between two rotatable polarizers. The physical parameters of the cell (twist angle α, director orientation ψ, birefringence β) can be retrieved if the Jones matrix is known for more than one wavelength. We have measured the Jones matrices of the TN-LC cells of a translucent Sony LCX-016 microdisplay for six wavelengths ranging from 488 nm to 1064 nm and determined the physical parameters of the cell. We have also measured the Jones matrices for one wavelength for a number of applied voltages. These experimental results show that it is not sufficiently exact to calculate the Jones matrix from the known physical parameters of the cell assuming a voltage-dependent birefringence only. We attribute the deviations from the theoretical model to edge effects which are not taken into account. The direct experimental determination of the Jones matrix components is therefore preferable and permits a more accurate simulation of the TN-LC microdisplay in experimental configurations involving other polarization-dependent optical components.

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We developed a new method for fabrication of oxide laser ceramics. Its prospects were conclusively confirmed by efficient lasing at two wavelengths ≈1064 nm (4F3/2 → 4I11/2) and ≈946 nm (4F3/2 → 4I9/2) of Nd3+ ions in Y3Al5O12 ceramics with laser‐diode pumping. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)