Pulse-shape improvement during amplification and second-harmonic generation of picosecond pulses at 531 nm

Abstract

We study second-harmonic generation of picosecond pulses in bulk periodically poled lithium niobate using an all-semiconductor master oscillator-power amplifier with gain-switched seed as our fundamental source. Both during amplification and during the subsequent second-harmonic generation, the signal pulse shape improves, and the resulting pulses at 531 nm are nearly independent of the seed pump conditions. Over a wide range of repetition rates and seed settings, we obtain green pulses with a duration of less than 31 ps FWHM and a peak power of more than 5.1 W. We further investigate the influence of the fundamental's spectral dynamics on pulsed second-harmonic generation efficiency and obtain excellent agreement between our measurements and previously published theoretical treatments.

Versatile Picosecond Laser Sources for Time-Resolved Fluorescence Microscopy and Diffuse Optical Imaging

“…A class of picosecond lasers sources based on the fiber-amplication of gain-switched DFB diodes are presented that show a wide range of operating parameters [7,8]. These light sources can be seen as a further expansion to the general single photon counting instrumentation particularly suited for time-resolved imaging methods in the life sciences and biomedical analysis [1][2][3][4][5][6].…”

“…1 and their operation parameters are summarized in Table 1 [7,8]. The fundamental components of these systems are a DFB laser diode, a cascade of rare-earth fiber amplifiers and an optional nonlinear wave-mixing component for second-harmonic or sum-frequency generation.…”

“…By realizing this type of flexibility over a large variety of emission wavelengths, different spectral windows within scattering media and a wide range of fluorophores available for these applications can be accessed. In the following, a class of laser sources based on the fiber amplification of gain-switched distributed feedback laser diodes (DFB) is presented that are aimed at fulfilling these requirements, particularly the necessity of elevated peak and average output power [7,8]. The general laser architecture provides a variable operation over the notable range of 1 to 80 MHz with pulse energies that span the pico-and nanojoule range in a free running or triggered mode.…”

Diode laser based light sources for biomedical applications

“…In order to achieve higher output power, additional amplification may be necessary. This can be realized by different methods using, e.g., fiber amplifiers, semiconductor optical amplifiers or tapered amplifiers in form of a master oscillator power amplifier (MOPA) configuration [217][218][219][220][221][222]. Using the latter scheme up to 6.5 kW of peak power were demonstrated [221].…”

“…Using the latter scheme up to 6.5 kW of peak power were demonstrated [221]. In order to obtain other wavelengths frequency conversion has been applied to generate short pulse emission, e.g., in the green, yellow, and near-infrared spectral range [217,218,222,223], respectively. The green spectral range can easily be obtained by frequency doubling ps-pulses at around 1060 nm.…”