ORCID Profile
0000-0002-1807-859X
Current Organisation
University of Sydney
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Publisher: Optica Publishing Group
Date: 14-09-2023
DOI: 10.1364/OME.499219
Publisher: Optica Publishing Group
Date: 09-02-2023
DOI: 10.1364/JOSAB.479629
Abstract: Non-reciprocal optical components such as isolators and circulators are crucial for preventing catastrophic backreflection and controlling optical cross talk in photonic systems. While non-reciprocal devices based on Brillouin intermodal transitions have been experimentally demonstrated in chip-scale platforms, harnessing such interactions has required a suspended waveguide structure, which is challenging to fabricate and is potentially less robust than a non-suspended structure, thereby limiting the design flexibility. In this paper, we numerically investigate the performance of a Brillouin-based isolation scheme in which a dual-pump-driven optoacoustic interaction is used to excite confined acoustic waves in a traditional ridge waveguide. We find that acoustic confinement, and therefore the amount of Brillouin-driven mode conversion, can be enhanced by selecting an appropriate optical mode pair and waveguide geometry of two arsenic-based chalcogenide platforms. Further, we optimize the isolator design in its entirety, including the input couplers, mode filters, the Brillouin-active waveguide as well as the device fabrication tolerances. We predict such a device can achieve 30 dB isolation over a 38 nm bandwidth when 500 mW pump power is used in the presence of a ± 10 n m fabrication-induced width error, such isolation can be maintained over a 5–10 nm bandwidth.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2022
Publisher: Optica Publishing Group
Date: 14-01-2022
DOI: 10.1364/AO.435309
Abstract: The polarization response of graphene oxide (GO)-coated planarized optical waveguides is used to determine the complex refractive index of GO film. GO films with thicknesses between 0.10 and 0.71 µm were coated on planarized optical waveguides. GO-coated waveguides exhibit large polarization dependent losses—and the polarization response depends strongly on the GO coating thickness. The response was used, together with finite element analysis, to determine the complex refractive index of the GO film. The complex refractive indices of GO films for both TE- and TM-polarized light at a wavelength of 1550 nm were found to be 1.71 + 0 . 09 i and 1.58 + 0 . 05 i , respectively. The uncertainties of n G O and k G O for TE-polarized light are ± 0 . 02 and ± 0 . 03 , respectively, whereas the uncertainties of n G O and k G O for TM-polarized light are ± 0 . 05 and ± 0 . 02 , respectively.
Publisher: Elsevier BV
Date: 10-2021
Publisher: Optica Publishing Group
Date: 24-10-2022
DOI: 10.1364/JOSAB.471940
Abstract: The low optical loss of G e 2 S b 2 S e 4 T e 1 (GSST) makes it a potential functional material for all-optical multilevel photonics memory devices that can operate in the optical telecommunication wavelength band. However, the same characteristic also restricted the tolerance of GSST phase change conditions using 1550 nm as an excitation light source. This work reports on the enhancement of GSST phase change condition tolerance using a graphene oxide (GO) intermediate layer on a polymer waveguide platform. The hybrid waveguide exhibits an insertion loss of around 1 dB and a maximum readout contrast of 25% between amorphous and crystalline states, with a step increase in readout contrast of around 5% per step. This work serves as a proof of concept for the implementation of a GSST–GO hybrid structure as an optical functional material in all-optical photonics memory applications.
Publisher: Optica Publishing Group
Date: 20-01-2023
DOI: 10.1364/OE.482871
Abstract: Microwave photonics offers a promising solution for frequency converting microwave signals, however, demonstrations so far have either been bulky fibre implementations or lacked rejection of interfering image signals. Here, we demonstrate the first microwave photonic mixer with image rejection of broadband signals utilising chip-based stimulated Brillouin scattering and interferometry. We demonstrate frequency down-conversion of carrier frequencies ranging from 10 GHz-16 GHz, ultra-high image rejection for a single tone of up to 70 dB, and 100 MHz and 400 MHz wide analogue signals with 28.5 dB and 16 dB image rejection, respectively. Furthermore, we down-convert 200 Mb/s quadrature-phase-shift keying signals with an error vector magnitude as low as -9.6 dB when simultaneously present interfering image signals are suppressed by the mixer.
No related grants have been discovered for Choon Kong Lai.