Tapered fused bundle coupler package for reliable high optical power dissipation

Abstract

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.

High-power fiber laser combination technology

“…They demonstrated their findings on the TFB 1Â7 splitter using a 1.00 mm core diameter, 0.22 numerical aperture (NA) input fiber coupled with seven 400 micron core, 0.22 NA output fibers, that were tested up to 860 W at 976 nm [12]. The TFB device has, so far, passed high power operation standards [13,14].…”

Fabrication of high-efficiency pump and signal combiner based on a thermally expanded core technique

“…The high signal insertion loss can limit the signal power and can also cause damage to the pump diodes [10]. High order modes will degrade the beam quality of the output light [4].…”

“…For the realization of all-fiber integration eliminating free-space components, fiber laser requires fewer components and mechanical parts, making them quite robust, reliable, and compact [3][4][5]. A high power all-fiber highefficiency signal and pump combiner is one of the key components for an integrated fiber laser or amplifier system.…”

Airclad fiber laser technology

“…50(11) 111609-4 challenge of using standard polymer-clad fused pump combiners for high-power is the light absorbed in the polymer coating and the adhesive used in the package. 30 Since modestripping cannot easily be employed, challenges due to local heating must be addressed.…”