Patent ID: 7920606

Claim:
Optical apparatus, comprising: a fiber-MOPA, the fiber MOPA including an arrangement for providing pulses of radiation having a fundamental wavelength, an arrangement for dividing the fundamental-wavelength pulses into first and second portions and directing the first and second pulse-portions into respectively first and second output channels, and first and second fiber-amplifiers in respectively the first and second channels for amplifying respectively the first and second fundamental-wavelength pulse-portions; an arrangement for generating second-harmonic radiation pulses from the amplified fundamental-wavelength pulse portions from the first fiber-amplifier; and an arrangement for sum-frequency mixing the second-harmonic radiation pulses with amplified second fundamental-wavelength pulse-portions from the second fiber-amplifier to provide pulses of third-harmonic radiation and wherein there are residual portions of the amplified fundamental-wavelength pulse-portions from the first fiber-amplifier remaining from the second-harmonic generation process, and wherein the apparatus includes means for preventing the residual portions from entering the sum-frequency mixing arrangement.