We demonstrate the amplification of a 1064nm pulse-programmable fiber laser with Large Pitch Rod-Type Fibers of various Mode field diameters from 50 to 70 μm. We have developed a high power fiber amplifier at 1064nm delivering up to 100W/1mJ at 15ns pulses and 30W/300μJ at 2ns with linearly polarized and diffraction limited output beam (M²<1.2). The specific seeder from ESI – Pyrophotonics Lasers used in the experiment allowed us to obtain tailored-pulse programmable on demand at the output from 2ns to 600ns for various repetition rates from 10 to 500 kHz. We could demonstrate square pulses or any other shapes (also multi-pulses) whatever the repetition rate or the pulse duration. We also performed frequency conversion with LBO crystals leading to 50W at 532nm and 25W at 355nm with a diffraction limited output. Similar experiments performed at 1032nm are also reported.
Light absorption in structural adhesives constitutes the main source of heat in tapered fused bundle (TFB) devices.
Efficient heat dissipation solutions were developed by studying these thermal loads. The relative merits of transparent
vs. opaque package designs were established experimentally. In the former, light escapes without being absorbed by the
package walls, whereas in the latter, the spurious optical signal is directly absorbed and dissipated. The fact that heat is
generated directly in the adhesive largely favors the opaque package, which offers more efficient heat extraction. By
using a thermally conductive package, a temperature rise of 1.1°C per Watt of dissipated power was measured. These
numbers demonstrate that passive heat sinking at 20°C is sufficient to allow reliable operation up to 45Watts of
dissipated power (1kW with 0.2dB optical loss) without compromising long-term reliability.
Fiber lasers have recently received a lot of attention after the dramatic increase in output power achieved from single fibers. In particular, Ytterbium doped fibers offer a very low quantum defect and a very broad emission between 1 and 1.1 μm. Triggered by the progress in high-brightness pump diodes and the availability of large-mode-area (LMA) gain fibers, several fiber lasers with output powers in the 1kW range from a single fiber have been demonstrated [1-4]. While these demonstrations typically employ a length of gain fiber pumped via free-space coupling and free space optics as the high reflector, there are fewer reports of integrated all-fiber laser cavities, e.g. . The availability of high-power fiber-optic components and the assembly thereof is therefore crucial for making this technology accessible for a variety of applications. Fiber lasers and amplifiers are very attractive light sources for applications requiring high power as well as excellent beam quality, because they are much less susceptible to thermo-optic distortions than conventional solid-state lasers. A transform-limited beam quality (M2=1) is possible even at kW level output power. Another advantage is the excellent overlap between the signal light and the pump absorption achievable in properly designed fibers. This allows a very efficient operation and up to 80% of optical conversion efficiency have been demonstrated based on the launched pump power . Once assembled, fiber-optic modules do not require alignment and are therefore inherently robust. The tight confinement of the laser light combined with the long interaction length in fibers also makes them prime candidates for high gain systems.