Distinguished Lecturer Program

Fiber communications support a wide range of residential, mobile and enterprise services, within core, metro, and access optical networks. The 5G and beyond wireless is expected to have a dramatic impact on the fiber infrastructure, bringing new severe requirements such as higher data rates, ultra-high bandwidth, lower latency, accurate synchronization, network slicing, ultra-high reliability and massive connectivity for many devices. Adaptive, flexible and efficient optical resource management, as well as agile bit-rates are the key technologies to exploit the whole bandwidth of single-wavelength, single-core and single-mode fibers. All-optical orthogonal frequency division multiplexing (OFDM) and Nyquist-optical time division multiplexing (N-OTDM) are the two most suitable approaches to efficiently generate Tb/s superchannels, by optically multiplexing subcarriers or by time interleaving short sinc-shaped pulses. The superchannels are generated in the optical domain, in a power-efficient way, also overcoming the restrictions related to the bandwidth of modulators and digital signal processing devices. A planar arrayed waveguide grating (AWG) can be designed to implement the conventional or fractional Fourier transform and efficiently generate OFDM and Fr-OFDM superchannels, that are less sensitive to nonlinear distortion and chromatic dispersion effects. The ultimate efficiency in physical resource exploitation can be achieved only in a truly flexible system, where it is possible to switch from OFDM to N-OTDM and vice versa, through intermediate fractional grids. Starting from experimental results of a novel approach for hybrid time-frequency multiplexing, this talk will focus on additional multiplexing domains, such as polarization, space, wavelength and code. Suitable AWG configurations can be designed for simultaneous frequency and polarization or mode and frequency multiplexing, as well as for generating optical codes in asynchronous code division multiple access (CDMA) and optical packet switching systems.

Infectious diseases and water are some of the greatest, most urgent challenges of the 21st century. III-nitride ultraviolet (UV) light sources, including light emitting diodes (LEDs) and lasers, are the only alternative technology to replace conventional power-hungry, hazardous mercury lamps for disinfection and water purification. Recent studies showed that AlGaN-based UV-C LEDs can readily shred genetic material of viruses and bacterial and achieve 99.9% sterilization of SARS-COV-2. In this talk, I will present the recent advances of AlGaN and BN nanostructures and heterostructures and their applications in UV optoelectronics, including the first demonstration of mid and deep UV laser diodes and tunnel junction UV-C LEDs with significantly improved performance. The recent development of far-UV-C LEDs, in the wavelength range of 207-222 nm, will also be presented, which has shown to be faster and far more effective than traditional UV-C light (~265 nm) in preventing the transmission of microbial diseases, while causing virtually no harm to mammalian skin or eye.

Microwave measurement refers to the acquisition of parameters of a microwave signal, device, and subsystem, or the identification of properties of an object via microwave-based approaches. Thanks to the broad bandwidth and high-speed analog signal processing provided by modern photonics, microwave measurement in the optical domain can provide better performance in terms of bandwidth, resolution, and speed which may not be achievable using traditional, even state-of-the-art electronics. This talk performs an overview of recent photonics-based microwave measurement techniques developed for broadband microwave measurements such as electric field, phase noise, instantaneous frequency, and spectrum. Photonics-based radars for high-resolution imaging and fiber-connected distributed antenna systems for precise position localization are also introduced. Based on the broadband spectrum measurement and radar detection, microwave photonics based cognitive radio for future green wireless communication is described and discussed. Emerging technologies in this area and possible future research directions are also discussed.

Infrared detectors and imaging systems are becoming increasingly important in a diverse range of astronomic, military, and civilian applications. In recent years, this field has gained significant attention while incorporating various material combinations and architectures into detector designs with a strong focus on applicability into clinical domains. Here, we will discuss some of our detector structures, their results, and our latest work on disease detection. Our study of the biomedical application of infrared includes exploration of an Affordable, Sensitive, Specific, User-friendly, Rapid, Equipment-free, and Deliverable (ASSURED) diagnostic regimen and testing its clinical feasibility for inflammatory bowel diseases (IBDs) and cancer (Breast, Melanoma, and Lymphoma) screening. Our study using Fourier transform infrared (FTIR) spectroscopy in attenuated total reflectance (ATR) sampling mode, analyzed  body fluids in order to identify reproducible,  stable,  and statistically significant differences  in spectral signatures of the IR absorbance spectra between the control and disease samples. These results show that serum samples can be used to detect the biochemical changes induced by these diseases. This technology can be further developed into a futuristic, noninvasive, personalized diagnostic tool for various diseases in which patient-to-patient differences in molecular signatures would allow the assessment of disease status and personalized drug management.

This presentation focuses on structure property/relationships in advanced materials, emphasizing multifunctional systems that exhibit multiple functionalities. Such systems are then used as building blocks for the fabrication of various emerging technologies. In particular, nanostructured materials synthesized via the bottom–up approach present an opportunity for future generation low cost manufacturing of devices. We focus in particular on recent developments in solar technologies that aim to address the energy challenge, including third generation photovoltaics, solar hydrogen production, luminescent solar concentrators and other optoelectronic devices.

As the age of cheap oil and fossil fuels is coming to an end, humanity will face an energy crisis. Many alternative energy sources have already been identified. However, there is no optimal solution to replace fossil fuels on a short time scale with new sources that are economically viable and environmentally sustainable in the long term. History reports disastrous consequences for human societies that exploited their resources in a non sustainable way, and arguably this is exactly what is happening today on a global scale. Evidence for climate change is overwhelming. This public lecture aims at describing a general picture of the looming energy crisis, particularly to promote awareness. Some possible solutions are discussed, involving the use of advanced materials and nanotechnology for energy saving, energy storage and energy conversion.

Imaging systems as well as human vision system have limited capability for separation of spatial features and this information can also be extracted only from depth limited range. The reasons to the resolution and depth of focus limitations are related to the effect of diffraction i.e. the finite dimensions of the imaging optics as well as the geometry of the sensor.   In this talk I will present novel photonic approaches and means to exceed the above-mentioned resolution and depth of focus limitations and show how those concepts can be adapted to micro endoscopy as well as to microscopy related configurations as well as embedded into ophthalmic device while aiming to correct visual deficiencies.   In the case of micro-endoscopy, I will show how projection of high-resolution wavelength dependent or time dependent random codes can enhance the resolution of the collected light. Those concept of wavelength and time multiplexing super-resolved imaging will also be demonstrated for imaging through biological scattering medium such as biological tissues and liquids as blood. The projected wavelength and time dependent high-resolution encoding patterns are sent via laser-based illumination fiber while the collected light is collected via ultra-thin multi-core imaging fiber-based endoscope.   Then, in the case of microscopy I will present how the resolution limit can go below sub-wavelength bound towards nanoscopic imaging while using label-free configurations involving time multiplexing (time dependent light collection) based upon label-free non-static nano-particles either moving in uncontrolled Brownian motion or being manipulated with light. The presented realizations either use metallic nanoparticles or silicon coated nanoparticles.   The last part of the talk will be related to extending the depth of focus of imaging systems in all-optical manner while introducing “interference” effect based extended depth of focal imaging (rather than diffraction and refraction based). The proposed extended depth of focus approaches will be implemented in ophthalmic usage on top of conventional spectacles, contact lenses and intraocular lenses while aiming to simultaneously correct various visual refractive errors, such as myopia, hyperopia, presbyopia, regular/irregular astigmatism, as well as their combinations. I will also mention how this interference-based extended depth of focus approach can be combined with nanoparticles and laser-based treatment of the surface of the cornea.