Signal Processing

The realization of suitable high-speed digital-to-analog converters, analog-to-digital converters, and digital signal processors has allowed advanced signal processing to offer substantial improvements in the performance and functionality of fiber-optic communication systems. In the transmitter, appropriate drive signals for an optical modulator are synthesized using digital signal processing and digital-to-analog conversion. This permits the generation of modulated optical signals with unprecedented control of the time-varying amplitude and phase. The transmitted signal can be pre-compensated to account for fiber dispersion, fiber nonlinear effects, and the filtering of reconfigurable optical add-drop multiplexers. In the receiver, the combination of coherent detection, analog-to-digital conversion, and digital signal processing is a particularly powerful approach. Coherent detection preserves both the amplitude and phase of the received optical signal in the photo-detected signal. This allows for post-compensation using digital signal processing that effectively mitigates linear transmission impairments and implements key receiver functions.

Topics currently being investigated include the following:

  • digital signal processing for transmitters and receivers in coherent optical fiber transmission systems,
  • techniques for assessing the implications of transmission impairments on system performance,
  • signal processing algorithms for compensating transmission impairments, and
  • spectrally efficient modulation formats including constellation shaping.

Research Funding

Current research activities are supported by:

Natural Sciences and Engineering Research Council



John C. Cartledge

Department of Electrical and Computer Engineering
Queen's University
Kingston, ON K7L 3N6

Telephone: 613-533-2935

Applying for Graduate Programs
People Congratulations Facilities


J. C. Cartledge

Members of LSRL

M. Bagheri, Ph.D. program

H. Miller, Ph.D. program

A. S. Kashi, Postdoctoral Fellow

Graduates of LSRL

R. D. Bespalko, M.Sc.(Eng) and Ph.D.

S.-H. Chung, Ph.D.

N. Deb, Ph.D.

C. Doggart, M.A.Sc.

A. I. Abd El-Rahman, Ph.D.

A. Gallant, M.Sc.(Eng)

Ying Gao, PDF

Yuliang Gao, PDF

J. D. Gaudette, M.Sc.(Eng)

C. J. S. Ito, Ph.D.

A. Jain, PDF

Y. Jiang, Ph.D.

A. S. Karar, Ph.D. and PDF

A. S. Kashi, Ph.D.

J. H. Ke, PDF

D. J. Krause, Ph.D. and PDF

L. Li, VRS

I. Monfils, Ph.D.

M. Owsiak, M.Sc.(Eng)

M. A. Rezania, Ph.D.

X.-F. Tang, PDF

P. Wang, M.A.Sc.

M. Yanez, Ph.D. and PDF

K. Zanette, M.A.Sc.

S. Zhang, Ph.D.

K. P. Zhong, VRS


  • 9 May 2019, Ahmed Abd El-Rahman successfully defended his Ph.D. thesis; external examiner Prof. Paolo Serena.
  • 11 June 2019, Aazar Kashi successfully defended her Ph.D. thesis; external examiner Prof. Gabriella Bosco.
  • 18 September 2019, John Cartledge received a Faculty of Engineering and Applied Science 125th Celebration Faculty Award.
  • 6 November 2019, Peng Wang successfully defended his M.A.Sc. thesis.
  • 13 November 2019, Aazar Kashi received her Ph.D. at the Fall convocation.
  • 21 November 2019, Linan Li's paper accepted for publication in IEEE/OSA Journal of Lightwave Technology.


  • 31 January 2020, John Cartledge and Ahmed Abd El-Rahman's paper accepted for publication in IEEE/OSA Journal of Lightwave Technology.
  • 17 June 2020, Nebras Deb's paper accepted for publication in Optics Communications.
  • 29 August 2020, Nebras Deb's paper accepted for publication in Optics Communications.
  • 25 November 2020, John Cartledge and Ahmed Abd El-Rahman's paper accepted for publication in IEEE Photonics Technology Letters.
  • 15 December 2020, Nebras Deb successfully defended his Ph.D. thesis; external examiner Prof. Shiva Kumar.


  • 9 March 2021, Aazar Kashi's paper "Neural Network Training Framework for Nonlinear Signal-to-Noise Ratio Estimation in Heterogeneous Optical Networks" accepted for presentation at OFC 2021.

Research Facilities

The Lightwave Systems Research Laboratory is equipped with:

  • 92 GSa/s, 32 GHz single channel arbitrary electrical waveform generator,
  • 65 GSa/s, 20 GHz four-channel arbitrary electrical waveform generator,
  • 68.2 GSa/s four-channel arbitrary optical waveform generator (Ciena WaveLogic Ai),
  • 39.4 GSa/s four-channel arbitrary optical waveform generator (Ciena WaveLogic 3),
  • equivalent-time sampling oscilloscopes with 80 GHz electrical sampling modules and 65 GHz optical sampling modules,
  • real-time sampling oscilloscopes with bandwidths of 32 GHz and sampling rates of 40 GSa/s (eight channels) and 80 GSa/s (four channels),
  • optical modulation analyzer,
  • transmitters for 32 Gsym/s QPSK and QAM modulation formats,
  • optical spectrum analyzers,
  • WaveShaper programmable optical processors,
  • 40, 50 and 70 GHz signal generators,
  • lightwave component analyzers (300 kHz - 3 GHz and 130 MHz - 20 GHz, 40 MHz - 65 GHz),
  • 100 Hz - 22 GHz lightwave signal analyzer,
  • 5 Hz - 500 MHz network analyzer,
  • four-port network analyzer,
  • 12.5 Gbit/s error performance analyzer,
  • 25 - 43.5 Gbit/s error performance analyzer,
  • 25 - 48 Gbit/s error performance analyzer,
  • 10 - 56 Gbit/s error performance analyzer,
  • 40 Gbit/s duobinary transmitter,
  • chirp measurement test sets,
  • polarization analyzers/synthesisers
  • single- and multi-channel wavemeters,
  • optical power meters,
  • piezoelectric micropositioning stages with automatic alignment, and
  • fusion splicers.

Active components include tunable lasers, self-pulsating lasers, DFB lasers, optical modulators (MQW Mach-Zehnder modulator, electroabsorption modulator integrated with a DFB laser, electroabsorption modulator, lithium niobate Mach-Zehnder modulator), erbium doped fiber amplifiers, semiconductor optical amplifiers, interferometric wavelength converters, complete lightwave receivers, and high-speed photodiodes. A wide variety of basic instruments, passive optical components, and active and passive, baseband and microwave components are available.