Sydney University

The research laboratories of the University of Sydney School of Physics node of CUDOS consist of six individual laser laboratories, a large common area housing an extensive suite of high bit-rate test equipment as well as a number of other projects and work stations, a laboratory devoted to the tapering of optical fibres and a clean room housing an automatic alignment system. The facilities are all housed within the School of Physics on the Camperdown campus of the University of Sydney.

BERT (Bit Error Rate Test) system

A SHF 12103/11100 system, in conjunction with custom-assembled pulse slicer, data modulator and high speed detection comprises the CUDOS 56G BERT test station. A large quantity of specialised optical test and manipulation hardware, including tunable continuous wave and high speed pulsed optical sources, optical filters and attenuators are assembled for the use by researchers who are engaged in testing transmission impairments in novel photonic structures, as well as new concepts in data regeneration using nonlinear optical means.

Optical sampling of high speed pulse trains (1.28 TBaud)

A system has been constructed and is currently under evaluation for optical sampling of high symbol rate pulse trains at rates up to 1.28 TBaud, as electrical measurement systems cannot respond to the high speed short optical pulses in such bit streams. This system is complementary to a commercial frequency resolved optical gating (FROG) system used for pulse characterisation in the CUDOS laboratories.

Coherent communications transmitter/receiver

A full coherent communications testbed is being setup. I/Q modulators and coherent receivers are in place to generate and detect signal with complex phase and amplitude modulation. A realtime Agilent oscilloscope with 62GHz bandwidth allows arbitrary signals to be recorded. In-house built software performs equalization and phase recovery to decode QPSK signals. We are working on upgrading the system with multi-level modulation to produce quadrature amplitude modulation (QAM) signals.

Automatic fibre-waveguide alignment system

A Newport AA-Modal 18 axis automated waveguide alignment station has been installed into a Class 350 clean room situated within one of the laboratory spaces in the School of Physics. Used in conjunction with a dedicated optical source and detector, this system is being used for testing the effectiveness of fibre-waveguide coupling schemes using purpose-built optical fibre taper devices.

UV fibre Bragg grating (FBG) prototyping and characterisation facility

Fibre Bragg gratings are written in-house in the laboratories at the School of Physics using a resilient custom-built UV-laser based near-field grating writing system. These gratings are used both as utilities in other optical propagation research projects, and also form the basis of a number of projects investigating the fundamental physics of the interaction of light with gratings. A swept-wavelength source (SWS) system is used for characterisation of the optical loss of the gratings written with this system and this system has been extended by CUDOS researchers to permit measurement of the dispersion.

System for producing Bragg and long-period grating structures in chalcogenide thin films.

In a development project complementary to the UV grating writing facility, researchers at the School of Physics are working on a system for imprinting resonant grating structures into photosensitive chalcogenide waveguides created at the Australian National University. This material is highly photosensitive and can be excited with relatively low power green light from a frequency doubled DPSS laser system. The preliminary results of this work have been highly promising and plans are underway to extend the system to longer sample lengths with the purchase of a precision translation stage. This work supports the creation of optical regenerators and optical “slow-light” buffers on photonic chips.

Facility for exciting Raman and other resonant and non-resonant nonlinearities in chalcogenide optical structures and in silicon waveguides.

An 80 MHz 8 ps Nd:YVO4 laser installed in one of the CUDOS laboratories is used to pump a dedicated optical parametric oscillator, generating pulses tunable in the wavelength range of 1398 – 1608 nm. This source is used for investigating Raman and other resonant optical nonlinearities within waveguide samples of chalcogenide glass supplied by researchers at the Australian National University. This measurement capability is also complemented by a pair of Raman fibre lasers emitting high energy CW light in the S-band (1455 and 1480 nm) as well as high-power optical amplifiers, and a large amount of ancillary test and measurement equipment.

System for measurement of optical dispersion in short lengths of optical fibre.

A system has been assembled for measuring the optical dispersion of short lengths of optical fibre over a broad wavelength range. This system employs a white light supercontinuum source and measures the dispersion using an interferometric technique and has been used to measure the dispersion of several photonic crystal fibres.

System for generation of femtosecond supercontinuum pulses.

Research is underway in the CUDOS laboratories at the University of Sydney into ways of optimising the generation of broadband white light supercontinuum by using tapering of photonic crystal fibre in the coherent (femtosecond) regime. 80 fs pulses from a mode-locked Ti:sapphire laser are used to generate the nonlinear spectral broadening, and a specialised extended wavelength optical spectrum analyser (Ando AQ6315E) and home-built frequency-resolved optical gating (FROG) acts to characterise the output pulse characteristics. This work is carried out in complement to the sophisticated physical system modelling capabilities developed by the researchers at CUDOS.

High resolution microscope (1500X) with 12 Megapixel camera and differential phase contrast attachment.

An Olympus BX71 microscope with up to 1500x magnification is a work-horse for examining the properties of prototype waveguide devices and tapered photonic crystal fibre devices.

In the CUDOS laboratories there are several purpose-built systems designed for the controlled tapering of optical fibres to sub-micron dimensions using the flame-brushing technique. These tapers are of interest both in their own right (for example, for creation of enhanced supercontinuum) and also as couplers in photonic chip access projects. The tapering capability is to be extended to permit the tapering of optical fibre drawn using the highly nonlinear chalcogenide glass under investigation in several of the projects in the Sydney University laboratories.

Fixtures for creation of long-period grating (LPG) structures in fibres and waveguides by acoustic, mechanical and thermal methods.

Research is underway and fixtures have been establlished for the purpose of writing long-period gratings into optical fibres and highly nonlinear glass waveguides using a variety of techniques, including acoustic, mechanical and thermal methods.