A 70-Watt green laser with M2<1.4 has been demonstrated. This green laser consists of an all-fiber-based IR pump laser
at 1064 nm and a frequency-conversion module in a compact and flexible configuration. The IR laser produces up to 150
Watts in a polarized diffraction-limited output beam with high spectral brightness for frequency conversion. The IR laser
is operating under QCW mode, e.g. 10 MHz with 3~5 ns pulse width or 700 MHz with 50 ps pulse width, to generate
sufficient peak power for frequency doubling in the converter module. The IR laser and conversion module are
connected via a 5-mm stainless-steel protected delivery fiber for optical beam delivery and an electrical cable harness for
electrical power delivery and system control. Both the IR laser and converter module are run through embedded software
that controls laser operations such as warm up and shut down. System overview and full characterization results will be
presented. Such a high power green laser with near diffraction-limited output in a compact configuration will enable
various scientific as well as industrial applications.
Spectral Beam Combination (SBC) of multiple fiber laser outputs has been shown to be an effective way to scale the
power of fiber laser systems while maintaining
near-diffraction-limited beam quality. The fiber SBC system maintains
many of the key advantages of individual fiber lasers, such as high efficiency, excellent beam quality independent of
output power and relaxed thermal management requirements. Several approaches to spectral beam combination have
been demonstrated including single grating in linear oscillator, single grating in master oscillator power amplifier
(MOPA), dual grating MOPA and dual grating ring oscillator configurations. Each of these variations has certain
advantages in terms of the system design and fiber laser requirements. In this paper we analyze the different approaches
and compare them in terms of combined beam quality, line-width requirements of the individual fiber laser channels,
power scalability and system complexity. The results obtained using the different SBC approaches at Aculight are summarized in the context of this analysis.
Optical communications networks require integrated photonic components with negligible polarization dependence, which typically means that the waveguides must feature very low birefringence. Recent studies have shown that waveguides with low birefringence can be obtained, e.g., by using silica on Si waveguides and by buried ion-exchanged glass waveguides. However, many integrated photonic circuits consist of waveguides with varying widths. Therefore, low birefringence is consequently required for waveguides having different widths. This is a difficult task for most waveguide fabrication technologies. In this paper we present theoretical and experimental results on waveguide birefringence for buried silver ion-exchanged glass waveguides. We show that the waveguide birefringence is on the order of 10-6 for waveguide mask opening widths ranging from 2 to 9 μm. The measured values are in good agreement with the values calculated with our modeling software for ion-exchanged glass waveguides. This unique feature of ion-exchanged waveguides may be of significant importance in a wide variety of integrated photonic circuits requiring polarization independent operation.