A laser beam delivery system is presented, consisting of a high power Neodymium :YAG Diode Pumped Solid State DPSS laser, a complete vision processing system for seam tracking, custom electronics consisting of firmware developed especially for this application, processing head, integrated beam shaping optics and an all optical compact actuator to steer the high power laser beam to a target substrate. Delivery of <800W average power was successfully delivered to the target substrate with a homogenous rectangular beam profile. Beam steering resolutions of <3μm were achieved and target tracking accuracies were 50μm, limited by the vision system. Development of custom software was required to interpret system latency and vision system deviations encountered under production conditions. The system has been in serial manufacture since Dec2013.
Laser stability is critical to many industrial applications but is often a source of confusion when specifying and
comparing different laser systems. This can be due to the variety of parameters characterized, the range of measurement
techniques available and the many alternative methods that can be employed to analyse and present the stability data.
High throughput semiconductor applications with sensitivity to individual pulse variations require high average power
systems with optimised pulse energy stability. We report stability characterisation and optimisation for a range of
frequency doubled Q-switched Nd:YAG laser systems with average power up to 650 W and peak power up to 0.9 MW.
The techniques used to refine the stability of the lasers are described and the stability of the lasers is compared before
and after optimisation. Stabilised industrial 532 nm laser systems are presented with pulse energy up to 63 mJ and peak
to peak pulse energy variation reduced by a factor of two compared to standard systems at 10 kHz repetition rate.
Unique properties of ultrashort laser pulses open new possibilities for broadband optical communications in both space
and terrestrial systems. Spectral slicing offers a promising approach to wavelength multiplexing using a coherent
broadband source such as a modelocked femtosecond laser.
We have realized a free-space spectral slicing and transmission system, with a spectrally sliced modelocked laser
delivering ~100 fs pulses at 806 nm as the "frequency comb" source. Spectral slicing was performed using monolithic
arrays of electro-absorption modulators (EAM) fabricated from quantum-well GaAs/AlGaAs semiconductor material
with a bandgap energy falling within the fs pulse spectrum. The array bars contained between 2 and 10 individually
addressable EAM channels and were packaged into modules with cylindrical micro-optics for efficient coupling of light
into and from the semiconductor waveguide.
By performing absorption measurements as a function of wavelength and voltage bias on the EAM, we identified the
spectral region where modulation depth was the largest. Wavelength slicing was achieved by fanning out the fs pulse
beam with a diffraction grating and coupling it across the full width of the EAM array. A modulation depth >12 dB was
achieved by probing adjacent spectral channels using ON/OFF keying.
In summary, we have demonstrated spectral slicing of femtosecond pulses with EAM arrays for free-space
communications. The technology can find use in other areas, e.g., instant chemical analysis and remote sensing, as
EAMs can modulate both the intensity and phase of randomly selectable spectral channels, allowing complex spectra and
waveforms to be generated in real time.