Laser system and method

A laser system comprising:

• a gain medium configured to amplify incident electromagnetic radiation;
• and,
• a nonlinear optical element configured to convert electromagnetic radiation amplified by the gain medium to a shorter wavelength,
• wherein the laser system is configured such that the nonlinear optical element produces output electromagnetic radiation having a coherence curve comprising a contrast ratio of less than about 0.1 at an optical path difference that is within the inclusive range of about 1.5 mm to about 2.5 mm.

A method of operating a laser system comprising:

• using a gain medium to amplify incident electromagnetic radiation;
• using a nonlinear optical element to convert electromagnetic radiation amplified by the gain medium to a shorter wavelength;
• and
• configuring the laser system to introduce mode competition and nonlinear effects such that the nonlinear optical element produces output electromagnetic radiation having a frequency spectrum comprising:
• a first peak formed of a first group of frequencies;
• a second peak formed of a second group of frequencies;
• and
• a trough that separates the first and second peaks,
• wherein the first and second peaks are the only dominant peaks in the frequency spectrum.

A method of operating a laser system comprising:

• using a gain medium to amplify incident electromagnetic radiation;
• using a nonlinear optical element to convert electromagnetic radiation amplified by the gain medium to a shorter wavelength;
• and,
• configuring the laser system such that the nonlinear optical element produces output electromagnetic radiation having a coherence curve comprising a contrast ratio of less than about 0.1 at an optical path difference that is within the inclusive range of about 1.5 mm to about 2.5 mm.