Research

Research Highlights

November 2022:

Papers Published at Cell Press Heliyon!

Reconfigurable high-order mode pass filter for mode-division multiplexing
In mode division multiplexing (MDM) optical system, the mode filter has become an inseparable part to reduce modal crosstalk and transmit the desired modes unabatedly. As filtering out lower-order mode is difficult, here we propose a reconfigurable structure of a higher-order mode pass filter consisting of two tunable mode converters and a directional coupler (DC) in a three-mode planar waveguide platform. By switching the working states of the mode converters, the structure can also be used as a fundamental mode (TE0) pass filter and hence dynamic output signals can be achieved. For the second-order mode (TE2) transmission, the simulated excess loss is ∼0.61 dB at 1.550 μm and the extinction ratio remains ≥24 dB (power ratio of TE0 & TE2 Launch) and ≥25 dB (power ratio of TE1 & TE2 Launch) at the entire C-band (1.530–1.565 μm). The device has negligible polarization dependence and hence the TM polarization exhibits similar results.
https://doi.org/10.1016/j.heliyon.2022.e11706
A review of higher-order mode pass filtering techniques
Mode Division Multiplexing (MDM) is regarded as a promising technology to overcome the bottleneck of the future demand for high data transmission rates. Multimode fibers are replacing traditional single mode fibers to cope with the increasing bandwidth requirements. MDM works with multiple light modes, and these modes are bound to be coupled with other propagating modes as they pass through guided media. A mode filter removes unwanted modes from the signal received at the receiver after demultiplexing. As a result, designing a highly potential high-order mode pass filter is desired to meet the capacity crunch using the MDM technology. Currently, remarkable research works have been conducted on mode filtering. This paper presents an overview of recent developments in mode filtering techniques along with their designs and fabrication processes. In particular, the mode filter made from different types of materials is reviewed to illustrate the potential of the designs in improving the system performance. Even though commercial success has not been materialized, this work will provide promising prospects in mode filtering techniques for increased flexibility and the choice of different mode filters.
https://doi.org/10.1016/j.heliyon.2022.e11705

Paper Published at IEEE Photonic Technology Letters!!

Multi-Function Mode Processing Device for Mode Division Multiplexing Optical Networks
In this study, we propose a configurable multifunction device for the mode division multiplexing (MDM) optical networks. The device can simultaneously function as low- and high-order mode block filters and a mode exchanger by selectively tuning different working states. We fabricated the device using standard microfabrication technology and the experimental performance of the device adequately follows the simulated performance. Particularly, the device exhibits a measured mode extinction ratio of 22.20 dB and 19.46 dB as a low-order mode block filter at 1.550 μm wavelength. The proposed device has great potential for use in a fully flexible and advanced MDM optical system.
https://ieeexplore.ieee.org/document/9274354

Paper Published at Optics Express!!

Scalable selective high order mode pass filter architecture with asymmetric directional couplers
We propose a novel design architecture to realize scalable selective mode filter based on the asymmetric directional coupler structure. In this structure, any arbitrary high-order mode can pass, whereas other unwanted modes are blocked. Furthermore, multiple optical modes can be blocked by only adjusting the structural parameters. As a proof of concept, we experimentally demonstrated a three-mode device and the scalability of the proposed structure is demonstrated by another design of four-mode filter. The proposed architecture offers scalability and high-design flexibility, and it has excellent potential to be used in advanced mode division multiplexing optical networks.
www.osapublishing.org/oe/abstract.cfm?uri=oe-28-19-28465

Research Interests

Optical communication system, integrated optics, mode division multiplexing, free-space optics, photonic devices, fabrication, micro-fabrication, communication engineering, and embedded systems.

Skills

Micro-fabrication

3+ years laboratory-scale micro-fabrication experience
Specialized in Photonic integrated circuit fabrication in the clean-room environment
Processes: Vacuum and plasma system operation, thermal and e-beam evaporation, sputtering, photo-lithography, reactive ion etching, wet etching of metals and lift-off
Hand on experience in micro-fabrication process development and specification

Testing and Characterization

Extensive experience in testing and characterising the performance of photonic integrated devices to measure optical, thermo-optic, and electro-optic characteristics.
Skilled in designing and developing test methods to execute experiments, analyse test data to incorporate test results into improved designs
Measurement of optical beam parameter, beam intensity profile displays in 2D, 3D, and cross-section configurations using Laser beam analyser and CCD camera system
Near field imaging and optical power measurement using edge couplers, tuneable laser source, polarization controller, objective lens, optical power meter, and CCDs.
Expert in the measurement of key performance parameters of photonic integrated devices such as propagation loss, insertion loss, polarisation dependent loss, and coupling loss
Thermo-optic and electro-optic characterisation of waveguide devices: Mach-Zehnder interferometer, symmetrical and asymmetrical directional couplers, ring resonators, and Y-junctions
Spectral measurement over 600 to 1700 nm wavelength using the optical spectrum analyser
Measurement of Refractive index using prism coupler system with Index accuracy: +/- 0.001, Resolution: +/- 0.0005 and Thickness accuracy: +/- (0.5% + 500nm) Resolution: +/- 0.3%
Testing optical waveguide vertical features using step profiler from nm to mm range

Modelling and Software

Extensive experience in analytical and finite difference modelling of photonic devices using RSoft
Positive and negative tone photo-mask design using L-Edit
MATLAB, Simulink and C
SimaPro, PSpice, Microwave CAD

Electronics

Analog and digital circuit design and analysis
Signal conditioning and processing using embedded systems
Hardware system development and prototyping

List of Publications

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