Tunable Lasers Tutorial

Understanding tunable lasers: dedicated to young laser apprentices


F. J. Duarte

Key words: course, courses, calculus, Dirac interference, Dirac's notation, electromagnetism, Feynman, Fourier, interferometric, interference, introduction, instruction, laser, laser physicist, lecture, linewidth, Newton, quantum, teaching, university, university degree.

Note: also available: Understanding lasers in simple words.

Sometime ago, I wrote a tunable lasers tutorial, or tunable laser tutorial, that has been fairly well received. Now I have written a succinct summary of the equations [PDF] needed to design narrow-linewidth tunable lasers and predict their coherence characteristics. Unfortunately these tutorials assume certain background in physics and optics which might not be available to most readers. Here I will attempt to describe what is needed in order to build up such a background. In fact, I'll go further. I will describe what you need to know and master in order to become a laser physicist. This will be done from the perspective of the most wondrous of lasers: the tunable laser. To appreciate what is needed to understand tunable lasers first it must be realized that tunable lasers integrate the knowledge base of various disciplines in physics and mathematics. Here are the three basic components:

In addition, you will need a background in various branches of mathematics such as matrix algebra, Fourier theory, Laplace transforms, Legendre polynomials, and differential equations. Once the fundamentals are in place you can familiarize yourself with solid state physics and gain media in the liquid and the gas phase.

Now some observations about optics: once you have all the basic tools in your archives you should be able to study and master the principles of geometrical and physical optics. Optics is beautiful and this endeavour should be fun. One aspect not mentioned previously, and essential to build new lasers, is manual ability. The alignment of a laser requires excellent eye to hand coordination. Optics demands a delicate and clever touch. You should be able to develop this skill interacting with simple opto-mechanical projects. The earlier the better.

Learning and becoming familiar with the topics just outlined can take years of study even after a first university degree in physics or optics is completed. The truth is: you'll never stop learning. However, after some level of competency is reached and after your peers recognize you as a laser physicist you will find that you will be able to contribute beyond the boundaries of laser physics. Indeed, you should be able to design and build optically-based instrumentation for industrial, scientific, medical, and astronomical applications. In other words, you will become an excellent experimental physicist with a sound understanding of useful theory. Besides the pleasure and joy of observing your creativity at work you might even encounter the rare privilege of making a few discoveries of your own... and remember always... walk as children of light (Ephesians 5).

Suggested Optics and Physics Reading


Here I mention two little known facts that have been largely ignored in the literature:

Note on laser safety: a laser laboratory must always be neatly organized and very clean. A laser laboratory is not a place for chaos or dust. Further, always follow the safety recommendations applicable to the class of laser at hand. Ignoring these observations could have extremely grave consequences.

Tunable Laser Tutorial

Understanding Lasers in Simple Words

First published on the 12th of March, 2005. ; Updated on the 7th of April, 2022.