title: Simplified intracavity phase plates for increasing laser-mode discrimination.
abstract: Recently, a new class of laser resonators was introduced that utilizes diffractive mirrors and an additional intracavity diffractive phase element. High modal discrimination and low fundamental-mode loss were achieved simultaneously by use of sinusoidal and pseudorandom diffractive phase elements. An intracavity phase element consisting of a simple single-step phase modulation is approximated by a Gaussian with a small radius. Explicit expressions are obtained for the modal-discrimination factor as a function of resonator parameters with a Gaussian output mirror. Numerical simulations are performed for a phase element with a step singularity in the phase function, the fundamental mode of this cavity being super-Gaussian. The modal discrimination of the cavity is studied for different radii of the single-step phase modulation, the position of the phase plate, and the cavity Fresnel number. Optimum solutions are found for a plane output mirror with either a striped or a circular shape.
authors.affiliation: Troitsk Institute for Innovation and Fusion Research, Troitsk 142092, Russia.
authors.forename: A A
authors.initials: AA
authors.lastname: Napartovich
authors.forename: N N
authors.initials: NN
authors.lastname: Elkin
authors.forename: V N
authors.initials: VN
authors.lastname: Troschieva
authors.forename: D V
authors.initials: DV
authors.lastname: Vysotsky
authors.forename: J R
authors.initials: JR
authors.lastname: Leger