Talk Titles: Integrated optic few-mode devices on thin film lithium niobate and Multiple support recovery from very few measurements per sample
Speakers: Archana K and Lekshmi Ramesh
Date and Time : October 29, 2021 (Friday), 5:00 PM to 5:45 PM
Talk 1 Abstract : Mode division multiplexing (MDM) is a remarkable strategy to meet the explosively increasing bandwidth requirements in optical communication systems and interconnects. This scheme harnesses the orthogonality of modes to scale the transmission capacity in communication systems. MDM technique necessitates the development of devices that support multimodes starting from waveguides to modulators and amplifiers, along with mode manipulating devices like mode multiplexers and mode converters. In this talk, I will discuss the design of different configurations of multimode waveguides on thin film lithium niobate platform. We will also delve into a specific type of waveguides called zero-birefringence waveguides. High-index contrast integrated photonic platforms like silicon on insulator and lithium niobate on insulator have very different properties for transverse-electric (TE) and transverse-magnetic (TM) modes. This necessitates the use of polarization diversity schemes that handle TE and TM modes separately and increase the system complexity. In this talk, the design of zero birefringence waveguides (ZBR) that possess same properties for TE and TM polarizations will be discussed. Dual mode waveguides are designed on thin film lithium niobate (LN) leveraging the anisotropy of LN. Such waveguides can avoid polarization diversity schemes and open new avenues for the development of polarization-independent multimode devices which are also very much needed in mode/polarization division hybrid multiplexing schemes.
Speaker 1 Biography: :
Archana holds a PhD degree in Integrated Photonics, Dept. of ECE, IISc. She also holds BE in telecommunication engineering and MTech in digital communication & networking from Visvesvaraya Technological University, Belgaum. She secured university 10th and 1st rank respectively in the above mentioned programs. She is a recipient of the 2015 Visvesvaraya PhD fellowship from Ministry of Electronics & IT, Government of India. She has a teaching experience of eight years in engineering colleges, teaching UG students. She has been a research scholar at ECE, IISc from 2015 to 2021 and has recently defended her thesis titled “Integrated optic devices on thin film lithium niobate for few mode optical communications”. Her research interests include Mode hybridization and multimode devices on lithium niobate.
Date and Time : October 29, 2021 (Friday), 5:45 PM to 6:30 PM
Talk 2 Abstract : In this talk, I will describe the problem of multiple support recovery, where we are given access to linear measurements of multiple sparse samples. These samples can be partitioned into l groups, with samples belonging to the same group having a common support. For a given budget of m linear measurements per sample, the goal is to recover each of the underlying supports, in the absence of the knowledge of group labels. We study this problem with a focus on the measurement-constrained regime where m is smaller than the support size k of each sample. I will describe a two-step spectral algorithm, where we first estimate the union of the underlying supports, and then use spectral clustering on a fourth order statistic of the data to estimate the individual supports. Under a general, generative model assumption on the samples and measurement matrices, we will see that this estimator can recover the supports with fewer than k measurements per sample, from roughly k^4 l^4/m^4 samples.
Speaker 2 Biography:
Lekshmi Ramesh recently completed her PhD from the department of ECE, IISc, where she worked with
Prof. Chandra R. Murthy and Prof. Himanshu Tyagi. Her interests are in the areas of compressed sensing,
statistics, information theory, and privacy.
