Polychromatic Laser Source Ultraviolet Spectrum Generation

The patent divides the spectral generation process into multiple independent stages: first four-wave mixing to generate intermediate wavelengths, then second four-wave mixing to reach shorter wavelengths, and finally spectral broadening to extend into the ultraviolet. Each stage operates with specific pump wavelengths and generates distinct spectral components, allowing the system to achieve broad spectral coverage while maintaining manageable complexity at each step.

The patent implements nested four-wave mixing processes where the output of the first mixing process serves as the input for the second mixing process. Specifically, the generated wavelengths from the first four-wave mixing (including anti-Stokes lines) become the pump sources for subsequent mixing stages, creating a cascaded structure that efficiently extends the spectrum without requiring entirely separate systems for each wavelength range.

The patent performs preliminary spectral transformations through two stages of four-wave mixing before attempting spectral broadening into the ultraviolet. The first mixing generates intermediate wavelengths including anti-Stokes lines, and the second mixing further transforms these to shorter wavelengths that serve as optimal pump sources for ultraviolet broadening. This preliminary preparation of the spectrum at specific wavelengths makes the subsequent ultraviolet generation feasible and efficient.

The patent systematically changes key parameters including pump laser wavelengths (using multiple pump sources at different infrared wavelengths), fiber dispersion characteristics (through microstructured fiber design), and nonlinear interaction conditions (through controlled pulse durations and powers) to enable each stage of the spectral transformation process, ultimately achieving ultraviolet generation that would be impossible with conventional single-stage approaches.