Abstract

I show that an axially pumped solid-state laser is able to support off-axis beams in a plane-concave cavity when the cavity length is adjusted within a region close to the hemispherical resonator configuration. These beams are characterized by the fact that even if an object is placed inside the cavity on axis in front of the concave mirror they can still oscillate off-axially in a V-shape path. One can further select and manipulate the desired off-axis beam by inserting a mask into the cavity. Experimental observations of cavity-length-dependent behavior of an Nd: YVO4 laser at different pump power show that the gain-assisted self-image property in the vicinity of the hemispherical resonator configuration is responsible for the formation of these beams.

© 2004 Optical Society of America

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References

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  1. V.Couderc, O. Guy, A. Barthelemy, C. Froehly, and F. Louradour, �??Self-optimized resonator for optical pumping of solid-state lasers,�?? Opt. Lett. 19, 1134-1136 (1994).
    [CrossRef] [PubMed]
  2. A. E. Siegman, Lasers (University Science Books, Sausalito, CA, 1986), p. 845.
  3. H.-H. Wu, �??Interpulse period doubling in a self-mode-locked Ti:sapphire laser,�?? J. Opt. Soc. Am. B 18, 1597-1600 (2001).
    [CrossRef]

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Figures (7)

Fig. 1.
Fig. 1.

Schematic of the experimental setup. LD, laser diode; CL, collimating lens; FL, focusing lens; LC laser crystal; OC, output coupler; S, screen; F, filter; CCD, charge coupled device.

Fig. 2.
Fig. 2.

Beam patterns measured from laser output as a function of cavity length. The cavity length is changed by 30 µm per step from (b) to (o) and by 800 µm from (a) to (b) and (o) to (p).

Fig. 3.
Fig. 3.

Beam patterns measured for the same conditions as fig. 2 except that the Nd:YVO4 crystal is rotated by 45°.

Fig. 4.
Fig. 4.

Beam patterns measured by inserting a wrench into the cavity downward at different positions to block a portion of beam path.

Fig. 5.
Fig. 5.

Beam patterns formed by inserting a mask into the laser cavity (a) - (d) with an opening at different positions and (e) with two openings.

Fig. 6.
Fig. 6.

(a) A plane-concave cavity, which corresponds to a hemispherical resonator for an off-axis ray by taking into account the refraction in the laser crystal. (b) The cavity length corresponds to a hemispherical resonator configuration as a function of the angle θ1 between the off-axis ray and cavity axis.

Fig. 7.
Fig. 7.

Laser output power as a function of cavity length. (a) Without and (b) - (d) with an object inserted inside the cavity on axis at different pump powers where (a) and (b) are 360 mW, (c) is 180 mW, and (d) is 50 mW.

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