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 Research
 

Research Interests

VCSEL-based self-mixing sensors for biomedical applications

The self-mixing phenomenon occurs when the laser beam is partially reflected from an external target and injected back into the laser cavity. The reflected light interferes or ‘mixes’ with the light inside the laser cavity and produces variations to the threshold gain, emitted power, lasing spectrum and the laser junction voltage. The resulting output power variations are usually monitored by using the photodiode integrated within the laser package. This phenomenon allows the laser to be used as an interferometric sensor incorporating the light source and the interferometer in one device thus significantly reducing the cost and the complexity of the sensing system.

The purpose of this project is to provide a practical and theoretical knowledge base for the design and application of a completely novel family of biomedical imaging sensors based on two-dimensional arrays of Vertical-Cavity Surface-Emitting Lasers (VCSELS).

Representative publications:

 

Y. L. Lim, R. Kliese, K. Bertling, K. Tanimizu, P. A. Jacobs and A. D. Rakić, “Self-mixing flow sensor using a monolithic VCSEL array with parallel readout”  Optics Express, 18 (11), 11720-11727, (2010)

 

R. Kliese, Y. L. Lim, T. Bosch, and A. D. Rakić, “GaN laser self-mixing velocimeter for measuring slow flows” Opt. Lett.. 35 (6), 814-816, (2010)

 

Y. L. Lim, M. Nikolic, K. Bertling, R. Kliese, and A. D. Rakic, "Self-mixing imaging sensor using a monolithic VCSEL array with parallel readout," Optics Express, 17 (7)  5517-5525, (2009).

 

J. R. Tucker, A. D. Rakić, C. J. O’Brien, A. V. Zvyagin  “The effect of multiple transverse modes in self-mixing sensors based on Vertical-Cavity Surface-Emitting Lasers,” Appl. Opt. 46 (4), 611-619 (2007)

 
 

   
     

Optical Interconnects using Arrays of Vertical-Cavity Surface-Emitting Lasers

This work is concerned with the design and implementation of free-space optical interconnects to replace conventional copper wire type interconnects commonly used in the current computer technology. While the interconnect channel density (number of channels/mm2) and delay are important factors for many digital computers, crosstalk and noise associated with increasing channel densities and currents are becoming a larger problem.

 The advantage of optical interconnects are that they would allow higher operational speed (GB/s), better Bit-Error-Ratio (BER), and reduced power consumption in comparison with the existing electrical interconnects in computer systems. We have developed design oriented models for microchannel and hybrid optical interconnect architectures based on Vertical-Cavity Surface-Emitting Laser (VCSEL) arrays.

 

Applied Optics Vol 46, Issue 13,  May 2007 (cover page)

Representative publications:

F-C. F. Tsai, C. J. O’Brien, N. S. Petrovic, A. D. Rakić, “Analysis of hexagonal array geometry for free-space optical interconnects with improved signal-to-noise ratio,”  Appl. Opt. 46 (13), 2434-2442 (2007)  

 F-C. F. Tsai, C. J. O’Brien, N. S. Petrović, A. D. Rakić, “Analysis of optical channel crosstalk for free-space optical interconnects in the presence of higher order transverse modes,”  Appl. Opt.  44 (30), 6380-6387 (2005)

  
 
     

Design and Modelling of Organic Microcavity Light Emitting Diodes

We are working on modelling, design, and optimisation of novel organic light emitting structures. 

Project is being conducted in collaboration with Prof Djurisic's group at The University of Hong-Kong, Hong-Kong, China and draws on our earlier successful work on compound semiconductor materials for surface-normal light emitters. 

Representative publications:

C. H. Cheung, A. B. Djurišić, C. Y. Kwong, J. Chan,  A. D. Rakić,  H. L. Tam, K. W. Cheah,  Z. T. Liu, W. K. Chan,  and P. C. Chui, “Dependence of the emission from tris(8-hydroxyquinoline) aluminum based microcavity on device thickness and the emission layer position,” Thin Solid Films 489 (1-3),  235-244 (2005)
C. H. Cheung, A. B. Djurišić, C. Y. Kwong,  H. L. Tam,  K. W. Cheah, Z. T. Liu, W. K. Chan,  P. C. Chui, J. Chan and A. D. Rakić, “Reduced angular dependence of the emission from Tris(8-hydroxyquinoline) aluminum based microcavity,” Opt. Commun. 248 (1-3), 287-293 (2005)

 

 

  
   

 

 

  
     

Automated Techniques for Optical & Electrical Characterisation of Vertical-Cavity Surface-Emitting Lasers & VCSEL Arrays 

We have developed a novel system for comprehensive testing of light emitters used in optical communication and sensing systems. Our system allows for electrical (DC and RF) and optical measurements on semiconductor lasers such as Light-Current, Current-Voltage, optical spectrum, intensity noise spectrum and CCD camera beam profiling. System allows for spectrally, spatially and polarization resolved imaging of coexisting transverse modes in surface-normal and in-plane light emitters.

Representative publications:

C. J. O’Brien, M. L. Majewski, and A. D. Rakić, “A Critical Comparison of High-Speed VCSEL Characterization Techniques,” J. Lightwave Technol., 25 (2), 597-605 (2007)   DOI 10.1109/JLT.2006.889362
     
 

 

  
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Last Updated: 18 April, 2011, 8:51pm