We describe unprecedented performance level from a femtosecond fiber laser system optimized for precision industrial micro-machining. The monolithic fiber chirped pulse amplifier chain enables system output of 215 μJ pulse energy, ~510 fs pulse duration and 16 W average power. We reveal the critical enabling technology to reach this unprecedented pulse energy level, the salient operating principles for the full chirped pulse amplification system, and the key experimental performance data for the laser system.
Ultrashort pulse lasers based on fiber optic architecture will play a dominant role in the spread of these lasers into research and industrial applications. The principle challenge is to generate adequate pulse energy from singlemode or quasi-singlemode amplifiers which have small cross-sectional area. We demonstrate a robust, all-fiber erbium amplifier system that produces >100 μJ per pulse with 701 fs pulsewidth and M<sup>2</sup> < 1.3. We will discuss the salient amplifier dynamics that influence the pulse generation, shaping, and propagation phenomena in state-of-the-art erbium fiber lasers. Furthermore, we show data relevant to applications and implementation of ultrashort pulse lasers.
We have consistently observed quasi-phase-matched second- and third-order second-harmonic generation in the reflection geometry from GaAs/AlAs multilayers. We have measured the second-harmonic pulse energies and polarizations for different pump polarizations, incident angles, and pulse energies.
We review our recent results on efficient generation of coherent blue/green light based on different configurations and structures. We have used second-harmonic generation with forward or backward configuration in short-period periodically-poled bulk and waveguide KTP to generate blue light. We have used backward second-harmonic generation to characterize periodically-segmented sub-micron KTP waveguides. By cascading second-harmonic generation and subsequent sum-frequency generation, we have generated coherent blue light in KTP and/or Ce:KTP crystals. We have also studied damage threshold of bulk KTP; we hope that we can eventually use it towards efficient generation of CW coherent green light.