Speckle-free femtosecond red-green-blue (RGB) source from a fiber laser driven spectrally efficient two zero dispersion wavelength fiber source

We report a novel ultrafast red-green-blue (RGB) laser source based on second harmonic generation from a two zero dispersion wavelength (TZDW) fiber continuum source. The TZDW fiber source consists of a custom-built Yb:fiber amplifier and a commercially available TZDW photonic crystal fiber (PCF) which enables low noise and efficient frequency conversion from the 1035 nm pump source to two spectrally localized pulses centered at 850 nm and 1260 nm with 39.6% and 33.7% power efficiencies. With angularly multiplexed simultaneous phase matching, we achieve mW average power of red, green and blue pulses at 630 nm, 517 nm and 426 nm from single pass second harmonic generation. With broad RGB bandwidths of 7.4 nm, 3.2 nm and 5.2 nm, the source is inherently speckle-free while maintaining an excellent color rendering capability with higher than 99.7% excitation purity of the RGB color primaries, leading to the coverage of 192% NTSC color gamut (CIE 1976). The reported source features a simple system geometry; its potential in power scaling is discussed with currently available technologies.