BEGIN:VCALENDAR VERSION:2.0 PRODID:IEEE vTools.Events//EN CALSCALE:GREGORIAN BEGIN:VTIMEZONE TZID:America/New_York BEGIN:DAYLIGHT DTSTART:20240310T030000 TZOFFSETFROM:-0500 TZOFFSETTO:-0400 RRULE:FREQ=YEARLY;BYDAY=2SU;BYMONTH=3 TZNAME:EDT END:DAYLIGHT BEGIN:STANDARD DTSTART:20231105T010000 TZOFFSETFROM:-0400 TZOFFSETTO:-0500 RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=11 TZNAME:EST END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTAMP:20231211T150440Z UID:AE3D99BD-5F8B-45BB-865C-072A2CB17B95 DTSTART;TZID=America/New_York:20231208T100000 DTEND;TZID=America/New_York:20231208T233000 DESCRIPTION:Abstract – Over a decade ago the phenomenon of coherent perfe ct absorption (CPA) drew attention to the existence of non-scattering or r eflectionless solutions to all linear wave equations\, in arbitrary dimens ions and for any structure larger than the wavelength of the exciting wave . In the case of electromagnetic wave scattering these solutions were show n to be the time-reverse of a corresponding laser system at its oscillatio n threshold\, but the phenomenon is even more general and has been observe d\, e.g. in acoustics\, AC circuits and with quantum matter waves. In CPA waves are perfectly trapped in a lossy resonator by interference and hence are ultimately completely transduced to another form of energy\, without any reflected waves. However\, in controlling the propagation of waves\, o ften the goal is not transduction but to guide waves into desired output c hannels without any reflection back into the input channels and without an y substantial loss of energy. Recently we have developed a general theory of reflectionless scattering of linear waves which encompasses both reflec tionless behavior via transduction (CPA) and reflectionless behavior via p erfect “forward” routing of waves\, which we term Reflectionless Scatt ering Modes (RSMs). This theory has the same structure and universality as does the original theory of CPA. In both cases one can show that countabl y infinite solutions exist at complex frequencies\, and to find steady-sta te harmonic solutions two things are necessary: 1) A single structural or material parameter needs to be tuned to move the solution to a real freque ncy. 2) The appropriate input wavefront must be imposed on the structure a t this frequency. An unstructured or incoherent wave at the same frequency will not be reflectionless\, and even can be strongly scattered. I will r eview experiments which confirm both CPA and RSM at optical frequencies an d other experiments at microwave frequencies which demonstrate functionali zed signal routing\, such a frequency demultiplexing\, based on RSMs. RSMs can exhibit a novel kind of spontaneous parity-time symmetry breaking eve n in lossless systems\, leading to novel resonance lineshapes\, which were previously observed by not fully understood.\n\nCo-sponsored by: Advanced Science Research Center - the Graduate Center - City University of New yo rk\n\nSpeaker(s): A.Douglas Stone\n\nRoom: 1st Floor Auditorium\, Bldg: AS RC\, 85 SAINT NICHOLAS TERRACE\, New York\, New York\, United States\, 100 31\, Virtual: https://events.vtools.ieee.org/m/387807 LOCATION:Room: 1st Floor Auditorium\, Bldg: ASRC\, 85 SAINT NICHOLAS TERRAC E\, New York\, New York\, United States\, 10031\, Virtual: https://events. vtools.ieee.org/m/387807 ORGANIZER:athielens@gc.cuny.edu SEQUENCE:11 SUMMARY:IEEE NY JOINT MTT AP PHO & NANO CHAPTER - SEMINAR: Beyond CPA: A Ge neral Theory of Reflectionless Scattering URL;VALUE=URI:https://events.vtools.ieee.org/m/387807 X-ALT-DESC:Description: <br /><p><strong><span style="font-size: 10.5pt\; f ont-family: 'Tahoma'\,sans-serif\; color: black\;">Abstract</span></strong ><span style="font-size: 10.5pt\; font-family: 'Tahoma'\,sans-serif\; colo r: black\;">&nbsp\;&ndash\; Over a decade ago the phenomenon of coherent p erfect absorption (CPA) drew attention to the existence of non-scattering or reflectionless solutions to all linear wave equations\, in arbitrary di mensions and for any structure larger than the wavelength of the exciting wave.&nbsp\;In the case of electromagnetic wave scattering these solutions were shown to be the time-reverse of a corresponding laser system at its oscillation threshold\, but the phenomenon is even more general and has be en observed\, e.g. in acoustics\, AC circuits and with quantum matter wave s.&nbsp\;In CPA waves are perfectly trapped in a lossy resonator by interf erence and hence are ultimately completely transduced to another form of e nergy\, without any reflected waves.&nbsp\;However\, in controlling the pr opagation of waves\, often the goal is not transduction but to guide waves into desired output channels without any reflection back into the input c hannels and without any substantial loss of energy.&nbsp\;Recently we have developed a general theory of reflectionless scattering of linear waves w hich encompasses both reflectionless behavior via transduction (CPA) and r eflectionless behavior via perfect &ldquo\;forward&rdquo\; routing of wave s\, which we term Reflectionless Scattering Modes (RSMs).&nbsp\;&nbsp\;&nb sp\;This theory has the same structure and universality as does the origin al theory of CPA.&nbsp\;In both cases one can show that countably infinite solutions exist at complex frequencies\, and to find steady-state harmoni c solutions two things are necessary: 1) A single structural or material p arameter needs to be tuned to move the solution to a real frequency. 2) Th e appropriate input wavefront must be imposed on the structure at this fre quency.&nbsp\;An unstructured or incoherent wave at the same frequency wil l not be reflectionless\, and even can be strongly scattered.&nbsp\;I will review experiments which confirm both CPA and RSM at optical frequencies and other experiments at microwave frequencies which demonstrate functiona lized signal routing\, such a frequency demultiplexing\, based on RSMs.&nb sp\;RSMs can exhibit a novel kind of spontaneous parity-time symmetry brea king <em>even in lossless systems</em>\, leading to novel resonance linesh apes\, which were previously observed by not fully understood.</span></p> END:VEVENT END:VCALENDAR