Petal-like modes in Porro prism resonators

Igor A Litvin,Andrew Forbes,Liesl Burger

doi:10.1364/oe.15.014065

Igor A Litvin, Andrew Forbes + Show 1 more

Open Access

https://doi.org/10.1364/oe.15.014065

Copy DOI

Abstract

A new approach to modeling the spatial intensity profile from Porro prism resonators is proposed based on rotating loss screens to mimic the apex losses of the prisms. A numerical model based on this approach is presented which correctly predicts the output transverse field distribution found experimentally from such resonators.

Highlights

Right angle prisms, often referred to as Porro prisms, have the useful property that all incident rays on the prism are reflected back parallel to the initial propagation direction, independent of the angle of incidence
In [3] for example, the kernel of the Fresnel–Kirchoff diffraction integral contains only the optical path length experienced by the beam, treating the prism as though it were a perfect mirror, with an identical ABCD matrix representation albeit incorporating the inverting properties of the prisms. This approach appears to be the preferred model for prisms [7], even though it does not explain the complex transverse field patterns found in Porro prism resonators
Considering the diffraction of a field propagating between areas of high losses, it is reasonable to suppose that the approach and theory presented here is the explanation for the observed petal patterns from Porro prism resonators

Summary

Introduction

Often referred to as Porro prisms, have the useful property that all incident rays on the prism are reflected back parallel to the initial propagation direction, independent of the angle of incidence. An initial planar wave front remains planar after reflection This property was initially exploited in Michelson interferometers to relax the tolerances on misalignment, and proposed in 1962 by Gould et al [1] as a means to overcome misalignment problems in optical resonators employing Fabry–Perot cavities by replacing the end face mirrors with crossed roof prisms. In [3] for example, the kernel of the Fresnel–Kirchoff diffraction integral contains only the optical path length experienced by the beam, treating the prism as though it were a perfect mirror, with an identical ABCD matrix representation albeit incorporating the inverting properties of the prisms This approach appears to be the preferred model for prisms [7], even though it does not explain the complex transverse field patterns found in Porro prism resonators. The model is developed in section (2) and its properties discussed, and applied in section (3) to the case of a marginally stable crossed Porro prism resonator with a polarizer as an output coupler

Porro resonator concept

Test resonator

Experimental set-up

Numerical modeling

Results and discussion

Conclusion