Generation of Laguerre-Gaussian modes in Nd:YAG laser using diffractive optical pumping

✍ Scribed by J.-F. Bisson; Yu. Senatsky; Ken-Ichi Ueda

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 228 KB
• Volume: 2
• Category: Article
• ISSN: 1612-2011
• DOI: 10.1002/lapl.200510008

✦ Synopsis

A beam of pulsed laser radiation at the wavelength λ = 0.532 μm was diffracted at a circular diaphragm to produce a hollow-shape intensity distribution in the near field. This light distribution was used to pump an Nd:YAG laser, resulting in the formation of an inversion profile with a minimum at the laser resonator axis and enabling the suppression of the fundamental mode. Under this condition, the oscillation at λ = 1.064 μm of Laguerre-Gaussian modes (LG~0m~) with low and high values of the azimuthal index__m__was produced in the gain-switching regime. By changing the geometry of the resonator, the size of its waist parameter was changed, enabling the selection of the mode with an index__m__that best overlaps with the inversion profile. Oscillation of LG~0m~modes with indices ranging from__m__=1 to more than__m__=200 was obtained. LG~0m~modes with__m__≤ 50 were produced using the dependence of the waist parameter on the length of the resonator near the boundary of its stability region. A LG~0m~mode of the highest order,m≈ 240 was obtained by building a miniature laser resonator and using a pair of diaphragms in order to form a sharper ring-shape pumping distribution. Applications of diffractive optical pumping and ``hollow'' LG~0m~laser beams are discussed.