In the field of microwave photonics, we prioritise the development of innovative devices and systems with an emphasis on applications in signal processing, antenna beam-forming, mm-wave communications and sensing (including for biomedical areas). Particular attention in recent work has been given to the application of integrated photonics (through collaboration with external foundries) to microwave photonics, an emerging field which is set to revolutionise a wide array of end-user applications. Projects to date have examined the following themes:
- All-optical processing of microwave signals
- High-speed optical transmitters and photoreceivers
- Ring resonators for bio-sensing applicationsRadio-over-fibre systems at 30 GHz and 60 GHz
- Photonic techniques (e.g. optoelectronic oscillators) for generation of microwaves
- Photonics for 5G applications
Our longer term objective is to further develop our test-beds in order to deal with modulated optical signals up to at least 110 GHz. With the growing maturity of integrated photonic fabrication services, we aim to develop a model similar to that used in integrated microwave engineering. This will comprise of device design and layout using industry-standard design software followed by full characterisation of fabricated chips using bespoke on-wafer test characterisation facilities as well as advanced packaging facilities.
The ultrafast photonics activity of EMPHASIS covers the wider area of optoelectronics consisting of applied as well as fundamental research over thebroad electromagnetic spectrum of UV to far IR and THz. State of the art Laser equipment required to cover the broad electromagnetic spectrum and supporting equipment is available from the research laboratories participating in EMPHASIS.One of the areas of photonics that we are active in is ultrafast laser science which involves the use of very short duration laser pulses (femtosecond duration 10-15sec ) for research and development. Ultrashort laser pulses, with durations approaching the timescales of fundamental atomic and molecular processes, have proved to be extremely useful in a wide range of scientific disciplines. They deliver energy so quickly that new non-linear processes are possible. Their short duration allows them to probe delicate living structures in biology and medicine without destroying them and make material modifications on the micron scale with minimal or precisely controllable heat effects. Furthermore these short pulses provide a mean of resolving the various processes and interactions in novel material helping in their understanding thus improving their properties requirement for device applications. In semiconductor devices for example high speeds and small distances are closely related. Transistors with effective lengths of only few tens of nanometers have electrons transit time that can be as short as a picosecond and sometimes as short as a few hundreds of femtoseconds. This very fact has motivated a great deal of interest in very small-scale electronic devices. In other words making semiconductor devices smaller allows a faster response. The development of such high-speed devices requires clear understanding of the various dynamical properties of carriers as well as phonons in semiconductors on an ultrashort time scale. For example, the maximum attainable speed of gallium arsenide field-effect and heterojunction bipolar transistors is limited by the rate at which electrons transfer between high-mobility and low-mobility region in the conduction band of this material. Another interesting example is the rate at which energy relaxation occurs in a semiconductor material, the rate for this process may be limited by relaxation of the non-equilibrium phonon generated during carrier equilibration. Ultrafast laser probing techniques have been playing a key role recently in understanding carrier dynamics in organic material for photovoltaic applications thus improving their efficiency. Similarly ultrafast technology is of fundamental importance in countless other application and research areas.
- S. Iezekiel, A. Perentos, G. Charalambous, R. Shmulevich, S. Ben-Ezra, Long-reach Hybrid Digital/RF Radio-over-fibre at 30 GHz for 5G Applications [Invited], ACP 2017 OSA Asia Communications and Photonics Conference, Guangzhou, China, November 2017.
- G.K.M. Hasanuzzaman, S. Spolitis, T. Salgals, J. Braunfelds, A. Morales, L. González, S. Rommel, R. Puerta, P. Asensio, V. Bobrovs, S. Iezekiel, I.T. Monroy, Minimization of Crosstalk in Multicore Optical Fibre Link using Real-time FPGA based Approach, ACP 2017 OSA Asia Communications and Photonics Conference, Guangzhou, China, November 2017.
- G. Charalambous, G.K.M. Hasanuzzaman, A. Perentos and S. Iezekiel, Optoelectronic Recirculating Delay Line Implementation of a High-Q Optoelectronic Oscillator, 2017 International Topical Meeting on Microwave Photonics Conference, Beijing, China, 23-26 October, 2017.
- G.K.M. Hasanuzzaman and S. Iezekiel, Self-oscillating optical comb generator based on optoelectronic oscillator, Proceedings Volume 10103: Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications X, SPIE OPTO, San Francisco, 1st February 2017.
- S. Iezekiel, Integrated microwave photonics: A key enabling technology for radio-over-fiber [Invited paper], SPIE OPTO. International Society for Optics and Photonics, San Francisco, Feb. 2017.
- G. Charalambous, G.K.M. Hasanuzzaman, A. Perentos and S. Iezekiel, High-Q Wavelength Division Multiplexed Optoelectronic Oscillator based on a Cascaded Multi loop Topology, Optics Communications, Vol. 387, pp. 361-365, 2017.
- G. Charalambous, A. Perentos and S. Iezekiel, "High-Q Optoelectronic Oscillator based on Active Recirculating Delay Line and Dual-loop Topology", IEEE Photonics Technology Letters, Vol. 28, pp. 2850-2853, Dec. 2016.
- G. Charalambous, G.K.M. Hasanuzzaman, A. Perentos and S. Iezekiel, Ultra-high-Q Optoelectronic Oscillator based on Bilaterally Coupled Loops, IEEE MWP2016, International Topical Meeting on Microwave Photonics, Long Beach USA, Nov. 2016.
- G. Charalambous, A. Perentos and S. Iezekiel, High-Q optoelectronic oscillator using an active IIR recirculating delay line, IEEE International Photonics Conference (IPC 2016), Kona HI, USA, October 2016.
- G. Charalambous, G.K.M. Hasanuzzaman, A. Perentos and S. Iezekiel, Optoelectronic oscillator based on class AB photonic link [Invited], 18th International Conference on Transparent Optical networks (ICTON 2016), Trento, July 2016.
- S. Iezekiel, Radio-over-fiber technology and devices for 5G: An overview [Invited paper], SPIE OPTO. International Society for Optics and Photonics, San Francisco, Feb. 2016.
- S. Iezekiel, M. Burla, J. Klamkin, D. Marpaung and J. Capmany, "RF Engineering meets Optoelectronics: Progress in Integrated Microwave Photonics," IEEE Microwave Magazine, Vol. 16, pp. 28-45, Sept. 2015.
- S. Iezekiel, "Microwave-photonic links based on transistor-lasers: Small-signal gain analysis", IEEE Photonics Technology Letters, Vol. 26, No.2, pp. 183-186, Jan. 2014.
- A. Perentos, F. Cuesta-Soto, A. Canciamilla, B. Vidal, L. Pierno, N. S. Losilla, F. Lopez-Royo, A. Melloni and S. Iezekiel, "Using a Si3N4 ring resonator notch filter for optical carrier reduction and modulation depth enhancement in radio-over-fiber links", IEEE Photonics Journal, Feb. 2013.