1. School of Applied Mathematical and Physical Science, National Technical University of Athens, Athens 15773, Greece
2. Department of Mathematics, Nazarbayev University, Nur-Sultan 010000, Republic of Kazakhstan
3. Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061, USA
4. School of Optics and Photonics—CREOL, The University of Central Florida, Orlando, Florida 32816, USA