Environmentally stable, near-infrared, mode-locked fibre lasers for industrial applications

Mode-locked laser systems that show robust operation in the presence of environmental instabilities are desirable for numerous applications in the defence sector and beyond. In this thesis I present the development of two such systems based on fibre-laser architecture and developed for applications in radar and lidar. An environmentally stable, 800 nm, laser operating at 7.2 GHz was developed with a timing jitter of 26 fs (integrated from 10 Hz to 10 MHz) for photonic assisted analogue to digital conversion. A novel method of active stabilisation of the Mach-Zehnder Modulator was demonstrated, which allowed turn-key operation and maintained low jitter mode-locking for > 50 hours. When combined with stabilisation of the cavity length, timing jitters of < 42 fs (10 Hz to 10 MHz) can be achieved for a temperature range of 0 oC to 50 oC. A 1.5 µm, passively mode-locked erbium fibre laser was developed for non-line-of-sight lidar applications. The laser had a native repetition rate of 22.6 MHz and an average power of 0.6 mW. The laser output was pulse-picked and amplified to provide a repetition rate of 11.3 MHz and an average power of 354 mW. An innovative strategy was demonstrated to mitigate Q-switching instabilities. The laser was validated to be robust against vibration, shock and temperature, as required for its intended application.

Grantor dc:publisher

Engineering and Physical Sciences

Year dc:date.issued

2021

Author dc:creator

• Hill, Calum

Advisor dc:contributor.advisor

• Reid, Derryck

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/10399/5024

OAI identifier oai:identifier

oai:ros.hw.ac.uk:10399/5024