Fibre Tapering Facilities
The fibre tapering facilities comprise three taper rigs, taper rig#2, taper rig#3 and taper rig#4.
Taper rig#2, uses a combination of three, 100mm travel AEROTECH stages, three 25mm travel Newport stages and a custom made rotational stage. Taper rig#2 is currently configured with a naturally aspirated, air/butane burner and operates with the standard flame brushing technique.
The system is capable of producing tapers in standard SMF and MM silica fibres and micro-structured fibres such as “Grape Fruit Fibre ” (GFF), and Photonic crystal fibre (PCF). Taper rig#2 is located next to the clean room and routinely produces micron and sub-micron diameter tapers for use as evanescent field probes to couple light into photonic crystal waveguides and micro-cavities. Nano-wire tapers down to 200nm diameters have been fabricated on taper rig#2.
To augment these capabilities, a microscope with a CCD camera is coupled with the taper rig’s translation stages to form a fibre taper profiler. This has a pixel resolution of 0.5um and this allows a user to produce tapers and then characterise their shape. The machine has a suite of custom design tools which were developed for the facilities.
Taper rig#3 was designed to taper chalcogenide fibre which is a soft-glass with a low melt temperature. Resistive heating is used. This facility has produced chalcogenide tapers as long as 25cm and low loss tapers with waist diameters down to 800nm. These are primarily used to produce dispersion engineered tapers for non-linear signal processing applications and low threshold supercontinuum generation. The taper rig has been routinely tapering 20cm long, low loss tapers having waist diameters between 1 and 2um in diameter and waist lengths of 5cm.
In addition to tapering As2S3 and As2Se3 fibres, preliminary developments in tapering polymer (PMMA) micro-structured fibres has also been undertaken.
Taper rig#4 is designed around 150mm travel, THORLABs stages. The rig uses a CO2 laser as a heating source. Whilst the laser is an industrial Class 4 laser, the taper rig system has been engineered to comply has a Class 1 product. The laser energy is incident onto a sapphire tubing furnace and the beam power is actively monitored and stabilised by an automatic gain control circuit.
This system has produced tapers to 1um in diameter with tapering loss as low as 0.03dB. The taper rig features automated taper design software, fibre profiler and is fully computer controlled. The tapering software interfaces for controlling all the rigs have a “similar look and feel”. After suitable training, this allows users to effortlessly transition and move been different machines. Taper rig#4 is suitable for tapering MM, SMF and micro-structured silica fibres.