A storage medium includes a base substrate, a first metallic layer, a first border region, and a first cover substrate. The base substrate includes a first side and a second side. The first side and the second side oppose one another. The first metallic layer defines a first pattern. The first metallic layer directly abuts the first side of the base substrate. The first border region extends about the first pattern. The first cover substrate is positioned against an exposed surface of the first metallic layer such that the first metallic layer is positioned between the first side of the base substrate and the first cover substrate. The first cover substrate is coupled to the first border region.

Examples are disclosed that relate to efficiently producing multiple laser beams of a harmonic frequency from a fundamental frequency beam. One example provides a laser system comprising a laser configured to output a fundamental frequency beam, a first harmonic-generation stage, and a second harmonic-generation stage. The first harmonic-generation stage is configured to receive an input of the fundamental frequency beam from the laser, and output from the laser system a first-stage harmonic frequency beam and a first-stage residual fundamental frequency beam. The second harmonic-generation stage is configured to receive an input of the first-stage residual fundamental frequency beam, and to output from the laser system a second-stage harmonic frequency beam.