Fiber Optic Tutorials

This is a continuation from the previous tutorial - Laser spiking and mode competition   \(\text Q\)-switching is a widely used laser technique in which we allow a laser pumping process to build up a much larger than usual population inversion inside a laser cavity, while keeping the cavity itself from oscillating by removing the cavity feedback or greatly increasing the cavity losses—in effect by blocking or removing one of the end mirrors. Then, after a large inversion has been developed, we restore the cavity feedback, or "switch" the cavity \(\text Q\) back to its usual large value, using some...

This is a continuation from the previous tutorial - Laser dynamice the laser cavity equations     1.  LASER SPIKING AND RELAXATION OSCILLATIONS As soon as the first ruby laser was operated, it was immediately evident that this laser did not wish to oscillate smoothly or continuously during the 1 millisecond or so duration of the pumping flash. Figure 1 shows in fact the pumping flash, and the extremely irregular and unstable laser oscillation that resulted, as reported in one of the publications by T. H. Maiman on the first successful operation of the ruby laser. (The initial transient in the...

This is a continuation from the previous tutorial - More on unstable resonators In earlier tutorials we analyzed the steady-state behavior of laser cavities using simplified interferometer models, with a few extensions into transient behavior, as in the cavity build-up equations. The objective in this tutorial is to give a more complete and systematic derivation of the combined cavity and atomic equations of motion for a real multimode laser. We will then use these equations of motion in later tutorials to analyze dynamic phenomena such as spiking, \(\text Q\)-switching, mode locking, and injection locking in lasers.     1.  DERIVATION OF THE LASER CAVITY...

This is a continuation from the previous tutorial - Unstable optical resonators Unstable resonators, as a consequence of both their practical utility and their complex analytical properties, have stimulated many clever extensions as well as detailed mathematical analyses. In this tutorial we review briefly some of these more advanced analytical techniques and inventions, and then introduce what may eventually become the most useful form of unstable resonator, namely, the "soft-edged" or gaussian variable reflectivity type of geometrically unstable resonator.     1.  ADVANCED ANALYSES OF UNSTABLE RESONATORS We first introduce in this section several of the more advanced analytical techniques for...

  This is continuation from the previous tutorial - Optical Fibers for biomedical applications     1.  INTRODUCTION Silica-based light-guide fibers have been produced and deployed with great success in spite of their well-known ‘‘brittleness.’’ For instance, techniques have been developed that allow long lengths (tens of kilometers) of such fibers to be drawn and coated in-line. The preform and draw processes allow production fiber that has a flaw-free surface with, essentially, the theoretical strength under the conditions of use/test \(\sim5.5\text{GPa}\) for most of its length. The few manufacturing defects that occur are eliminated by a proof-testing procedure that allows the remaining...