Hi, I am your Nufern photon. Most people are familiar with electrons and electronics. Similarly, we, photons enable a whole field called photonics, the science of light. I’m gonna talk to you a little about light, optical fibers and the development of optical fiber lasers.
Photons can be portrayed as either particles or waves, mathematically. But, for our purposes, we will use a hybrid. Also, in my presentation, some technical terms will be in italics. This way, you’ll know __ might __ external references. For instance, wavelength, represented by the lower case Greek symbol, __.
In the optical spectrum, ‘wavelength’ refers to the color of light. Blue is a shorter wave length, around 400 nanometers, and red is a longer wavelength, around 700 nanometers. Light, of course, extends through a far greater spectrum than a human eye can see, from x-rays through to __ radiation. Most optical systems operate from the UV through to the infrared.
Optical fibers became possible with __ practical understanding of S__ law; Light transitioning between transparent materials bends in proportion to the change in its velocity, like a rod in a b__ appears bent at the air-water interface. The ratio of the velocity difference is the reflective index. In optics, we have materials called d__ into __ glass to change the reflective index. By putting two pieces of glass with different reflective indices __ __ each other, we can emulate the bent-rod effect. Imagine that a glass rod with a high reflective index core surrounded by a low reflective index / surrounded by / continuously down its a__. Well, that’s exactly what happens. And we can also change the effect of __ __ which light is accepted by adjusting / of the two glasses. This is called the numerical aperture.
High numerical aperture means __ broad__ angles of acceptance. If the core size is large so that multiple / can enter by a variety of angles __ can propagate down the core, the core is considered to be multi-moded. If the core size is small enough to only allow the passage of one wavelength at a specific injection angle, the core region is considered to be single-mode. Depending on the size of the glass rod, the reflective index and the wavelength, the core / both single- or multi-moded. We strive for single mode.
So, we generate certain wavelengths and use glass rod__ / with / micrometers, less than two human hairs / small enough to be greatly flexible and r__: fibers. / Fibers usually have one core and one __ing along a protective coating. Most are made of __ glass because of its purity / standardized n__ to specify the relative size of the core to the __. For example, __ represents a single-mode fiber with a core of 10 micrometers in diameter and a __ing of 125 / micrometers / core / micrometers / core / is represented by __.
Even though we know we can send light down a fiber, there are many variables that come into play: fiber type, core size, numerical aperture, reflective index and d__ing … all contribute to expand the range / possibility / propagation. However, we strive for / single mode, remember? / down / fiber / is difficult and the light source is expensive. How can we strike a balance between / power, efficiency and economy?
Through experimentation / changing the reflective index / periodically along / make / reflect light. This creates / that takes advantage / type of mirror / by changing the intensity in period of __ __, / amount of / particular / can also be controlled. This quickly led to the development of __ fiber laser / fiber laser works by reflecting / stream of photons stimulates atoms that store and release light energy __ use__ wavelength__ /
on the periodic chart, these / series / most common __ atom. __ __, a pioneer of optical fibers, __ to dope the core of / optical fiber with __ __ to control the reflective index and photon absorption / Practically speaking, the __ atoms / absorption curve that looks like this. / broader s__ of light / can be / shorter __ n__ wavelength / and / more / slightly longer but narrower __ nanometer wavelength / the photon__ absorbed by the / disappears / and / electrons / to a higher orbital / absorbed energy. This process is called / and stored by, the atoms in the fiber / within about a millisecond / otherwise / drop / to __ original, or ground, state / __ nanometers. The energy / re-emission is known as / quantum efficiency / simply the ratio of the / over / wavelength. It’s impossible to get a higher optical efficiency than this number.
/ can be made to raise / astounding optical efficiency. / pump / over and over again __ __ realistic over-simplification of the process. To maximize the coordination of the pumping __ emission / fiber-optical cavity, sometimes called a r__, / constructed / end of the cavity / reflector / spliced / doped with __ __ atoms / at the output end, __ similar / around 10% __ installed / thus, a very simple / created / in fiber terminology, means that, once / in the fiber / it stays in the fiber, end to end / however / is important as it determines how much of the __ light / use the term / absorption length / with the amount of doping.
Typically / about 95% of the pump energy. This is to avoid / un-pumped / in the laser cavity. / inevitably / itself / fiber / optical laser diode can be installed / the pump end / power is limited to / output / single-mode / times the quantum efficiency of the laser / single / expensive and relatively low-power__ / to achieve / higher / even / get connected to / fiber / fiber / get much fatter. In fact / both __ __ be / it was discovered that, once / continue / even / tail / essentially gone. The light __ can __ be re-captured / path / This path / called / field.
By extending this / multiple / or split out of, __ __ field / leading / to / limit / must be conserved. For example, a coupler / made / micrometer / numerical / with / numerical aperture / change / by adding / new / we can see / doubled / for __ effect / require / diode / ultra-high brightness / ultra-high price / not practical at all.
/ numerical aperture / larger diameter / using these economical / use / double-__ / The invention of / fiber / economy / great / astoundingly high / In principle, a double / we__ just described / is larger in diameter / second / with a very high / even / allow / six legs / each. Pumps / This is encouraging. Once / apply / power / much of / simply passes down / without / the core. Without this intersection, / laser / work / solution / create / remember him? … found / shape / re-distribution / core.
Now we / situation / too much / up / few / behave / much like / highway / such / and / solution / highway / more lanes / core / reduces
