Saturday, August 19, 2017

Why this New Book on Nonlinear Optics?

My new book on nonlinear optics is out (see tinyurl.com/y83o3tsg or  https://www.createspace.com/598976 ).  I've been working on this for a while and I am pleased that it is finally out.  Why did I write this volume?  The reasons are both intellectual and altruistic.

First, the material that I cover in this text may overlap that of other books, but I add unusual topics, provide a different emphasis, and dig deeper into ideas that provide insights.  Also unique to this volume are the problems, which I have designed to be instructive, as well as the use of Python (or any other language) to solve problems numerically.  I feel that producing such a volume was worthwhile and will be useful to anyone wishing to learn about what I believe to be a very interesting subject.

Secondly, physics textbooks usually cost about $100, and sometimes much more.  This volume is an inexpensive alternative for those of us who like paper.  I originally decided to self publish because the physical book costs less to buy than making a paper copy with an inkjet or laser printer.

The production of a quality physics book takes great effort, and the fixed editorial overhead is difficult to recoup when the sales volumes are low, as is the case for advanced texts.  This makes the high costs justifiable.  Self publishing greatly lowers the costs by eliminating the profits made by publishers and the small royalties given to authors.  The downside of self publishing for a dyslexic sort such as me are typos, misspellings and small errors that I don't catch.  My students who have used this book in class prior to its publication have helped, but they can't be faulted for missing lots of errors.

pdf format is fine for novels and other works that are linear in nature, but physics requires lots of jumping around, which becomes cumbersome with any electronic format.  In my opinion, nothing beats a physical book when studying physics.  I stand behind this conviction with my personal resources, providing this paper book free of charge to my students.  I will not make a pdf file generally available, but will allow open access software to have a pdf copy if it adds value to the student.

I welcome feedback and will diligently fix errors that are brought to my attention.  A also look forward to getting your frank opinion, which I will take into account when producing future volumes. 

Below is the publisher's description and an excerpt from the preface.

Description

This unique textbook on nonlinear optics is written by award-winning teacher and researcher, Regents Professor Mark G. Kuzyk of Washington State University.  It is ideal for a class or as a reference, and can be used for self study.  Exercises are provided as material is introduced to reinforce concepts.  The book's approach mirrors the author's philosophy that a firm grounding in the fundamentals will allow the student to tackle any topic.  As such, many topics are left out while others are covered in depth to develop the intuition.  Physics is meant to be savored, so this book should be consumed slowly with attention to the deeper meaning of the topics presented.  The rest will naturally fall into place.

Material not normally discussed in standard textbooks that is covered here includes the introduction of second quantization and how it can be applied to Feynman-like diagrams for calculating nonlinear susceptibilities.  Dirac notation is introduced to facilitate the development of the theory with finesse.  This approach provides a pictorial representation of light-matter interactions that leads to a more intuitive understanding of phenomena such as difference frequency generation, cascading and stimulated emission.  An introduction to Python programming and solving simple numerical problems is briefly presented to get the student up to speed.  In addition to unique problem sets that are not typically assigned in a course on nonlinear optics, a series of numerical problems are provided to both hone coding skills (the student can code in any language) and shed light on problems that have no analytical solution.

Other unique topics covered are magnetic susceptibilities, nonlinear optics at negative absolute temperature, epsilon near zero materials, surface plasmons in various spatial dimensions, aperiodic nonlinear gratings to control the effective nonlinearity, nonlinear optics of single molecules, self-consistent methods for treating cascading as a local field and an in-depth derivation of optical multi-stability.

This book is a total overhaul of "Lecture Notes in Nonlinear Optics: a student's perspective." Previous material is extensively augmented and rewritten for clarity and lots of new material has been added.  While this newer book tries to take a student's perspective, it does not have the same raw narrative as the previous volume.  Being so different in approach and content, it should be considered a new book rather than an updated edition of the previous one.  If the more polished approach is not your thing, then go for the older book, which will remain available indefinitely.

Excerpt from Preface

As a new faculty member at WSU, I was trying to explain a concept to a confused student in an introductory physics class.  I called upon analogies, attacked the ideas from various perspectives, and drew all sorts of diagrams, but that blank stare never went away.

On his way out, he ran into a graduate student who he recognized as a teaching assistant from a previous semester, and stepped into his office to chat.  The source of his confusion came up.  I eavesdropped, listening to the graduate student's bumbling and inaccurate explanation, fearing that the undergraduate's understanding would be irreversibly damaged.  Instead, he excitedly exclaimed, ``Now I understand.  You're great at explaining physics."

Over the years, I have witnessed this phenomena many times and at all levels.  I have concluded that the very best students learn from a clear and rigorous explanation; but, most mortals learn in a process that is akin to an image coming slowly into focus.  Like a photographer adjusting her lens back and forth several times, I believe that students learn by overcoming stages of confusion.  Compatriots with an understanding that is one step of fuzziness ahead are better able to mediate the next transition.  This was my original motivation for publishing the book, ``Lecture Notes in Nonlinear Optics: A student's perspective."  What better way to explain complex topics than from the perspective of students who have just learned it, with recent memories of the obstacles that they had to overcome?

When I taught Nonlinear Optics in spring 2014, I read the book in parallel to preparing for class, which made me better able to judge the book's effectiveness.  While the book is adequate for this purpose, I found three issues that compelled me to work on this volume.  First, some of the nuances that make nonlinear optics interesting were not properly explained.  Secondly, topics which are unique to the way I teach the course were absent.  Finally, I felt it was time to add more original homework problems, the kinds that have helped me to understand the material better, and I hope will be useful to the students.  Additionally, many of the typos and grammatical errors were fixed, poor quality figures were redrawn, and redundant materials were eliminated.

While textbooks should focus on the fundamentals, I felt that integrating some programming into the book would not only be instructive, but fun.  New to this book are sections on using Python for modeling nonlinear-optical processes as well as some very simple problems that require only basic coding skills.  This addition serves two purposes; it teaches students how to solve problems numerically, but most importantly, it allows a broader range of problems to be solved, giving the students a deeper appreciation of nonlinear optics.

My original intention was to produce a second edition of ``Lecture Notes in Nonlinear Optics: A student's perspective."  However, since the spirit of the book has changed, and the present volume is a far cry from lecture notes, I decided to start fresh with a new title and a new approach.  Many of the students liked the raw feel of the original book while others were annoyed by it, including me.  As such, I have decided to continue to make the older book available even after releasing this volume. Perhaps many of you will find this new volume objectionable, but I disagree.  We'll see how it all plays out.

I believe that this book is amendable to self study.  The student should read it cover to cover and solve all the problems along the way.  Many of the problems are short and presented right after the relevant material, providing realtime practice while reading.  I originally intended to produce a solution manual, but after decades of teaching, I am convinced that such a crutch is just too tempting.  Students who peek prior to substantial effort will develop a false sense of understanding that will unravel when their knowledge is put to the test.


Friday, August 18, 2017

New Physical Review Leters Paper is out



Researchers at Washington State University use Patterns to set Limits on Light/Matter Interactions


 

Physicists Rick Lytel, Sean Mossman, Ethan Crowell and Mark Kuzyk at Washington State University are developing general principles that can be applied to making new materials that harness light.   Beefed up light-matter interactions can be used to make higher-contrast medical images, more effectively burn cancer cells while leaving healthy ones intact, suppress the twinkle of stars in telescopes, supercharge the internet, make lasers more colorful and effortlessly process complex images.  The new has appeared in the August 18th 2017 issue of Physical Review Letters.

Researchers typically model each new candidate material with complex equations that are difficult to interpret.  Rather than evaluate specific materials using this obtuse formalism, the WSU team instead studies the structure of the equations to search for patterns that hint at the largest possible response.  Since the equations are intractable, the researchers instead throw metaphoric darts at the target, but constrain the trajectories using the sum rules -- physical laws that must be obeyed by a quantum system.  After many throws, and applying a filter that takes into account the effect of molecule size, a pattern comes into focus.

The pattern reveals the true fundamental limits to be about 30% lower than previously calculated and suggests that a potentially new design paradigm will be required to get to the limit.  Ongoing work is aimed at translating the physicists’ esoteric findings into rules that can be used by chemists, materials scientists and nanotechnologists to make better materials.

The present work resolves several puzzles.  The theory of the fundamental limits of light/matter interaction strength predicted a ceiling that was almost 50% higher than all theoretical models, suggesting that exotic materials were needed to bridge the gap.  The new work shows that such unphysical quantum systems are not required to reach the limits and that exotic systems will likely obey the same limit.  Furthermore, infinities in the older incomplete theory – warning flags in physics of theoretical pathologies -- have been excluded by the new results.

While the present work has practical implications for new technologies, the search for patterns generated by constrained random sampling is a powerful tool that can be applied to understanding the underlying structure of complex theories.  In future work, the WSU researchers plan to apply this approach to a holistic investigation of the combined properties of a material needed for specific applications, and identifying the path for getting there.