Laser gain media

This fiber technology has also been used to fabricate glass fiber laser gain media. In this case, the core is doped with laser-active elements with a higher refractive index, whereas the cladding layer does not contain laser-active elements with a relatively lower refractive index. When a long and narrow glass fiber, with a... 

Pirri A, Toci G, Vannini M (2012) Characterization and comparison of 1 % at Yb-doped LU2O3 and SC2O3 ceramics as laser gain media. Laser Phys 22 1851-1855... 

Laser History Laser Gain Media Laser Beam Properties Laser LInewldth Laser Wavelengths Types of Lasers... 

To investigate materials such as laser gain media only simple experimental techniques are usually required. To evaluate the potential of a new material in a technological application it is often sufficient to measure absorption and emission spectra along with luminescence lifetimes, though it is desirable to also have an indication of relevant loss mechanisms. These include nonradiative decay, excited state absorption and energy transfer. The result of significant nonradiative decay is indicated by variations in luminescence intensity and lifetime as a function of temperature... 

For laser experiments the as fabricated waveguide was used as the laser gain medium without any coupling of external reflectors (mirrors). The experimental set-up used for laser gain experiments is schematically shown in Fig. 2. Optical excitation of the channel waveguide was performed by end-fired coupling a Ti sapphire continuous wave laser operating at 748 nm transition). 

Luo D, Zhang J, Xu C, Yang H, Lin H, Zhu H et al (2012) Yb LuAG laser ceramics a promising high power laser gain medium. Opt Mater Express 2 1425-1431... 

A laser cavity tends to select specific wavelengths (Fig. 5) within the normal gain bandwidth of the laser gain medium... 

It should be noted that, depending on the particular laser gain medium and resonator configuration, oscillatory start-up behaviour might be encountered. For example, CW Nd YAG lasers frequently exhibit this behaviour. However, for long-time continuous operation this is irrelevant, since an experiment can easily commence after the switch-on oscillations have died down (in the worst case they will last for a few milliseconds at most). 

Figure 9.1 A laser cavity. The laser gain medium has physical length L the end reflecting mirrors M have light intensity reflectivities and r. ...

The best known materials that have been developed over the last four decades are for implementation in lasers, either as gain media or as saturable absorbers. The first laser gain medium was ruby (see Figure 2), providing single wavelength output in the visible part of the spectrum. Neodymium based lasers have now largely replaced ruby as the industrial laser of choice. The i/2 electronic transition (see... 

In this section, we describe a simple laser setup using a high-gain medium consisting of DCM-encapsulated dendrimers in a methanol solution. The results can be applied to a solid-state laser medium [42], described in the next section. In that case, we used RdB-dendrimer in the waveguide gain medium [43]. 

All lasers have the following three fundamental components (see Figure 1). The gain medium, the business end of the laser, is the medium in which excited states are created which will produce stimulated emission. The exciter is the source of energy for production of the excited states in the gain medium. Finally, the optical resonator determines the directionality, wavelength selectivity, optical feedback, polarization, and other characteristics of the stimulated emission from the gain medium. 

A number of points are clear. First, in all cases the major expense of laser photons is the hardware, not the energy (even at Austin prices). Secondly, the intrinsically greater efficiency of the lower-energy lasers, especially the economic attractiveness of the CO2 laser, is evident. One can easily understand why laser chemistry schemes based upon multiphoton infrared absorption attract so much effort. Thirdly, on a per-unit-time basis the ion laser is more than twice as expensive to operate than even the rather exotic excimer laser. This is because of the inherent energetic inefficiency of the rare-gas plasma as a gain medium and because of the extrinsic, and hideous, expense of ion laser plasma tubes (and their poor reliability). 

Principal components of a laser (1) Gain medium (gas, liquid, or solid crystal, e.g,. ruby) inside the optical cavity, (2) input pumping energy (e.g., from flash lamp), (3) high-efficiency reflector ( 100% reflectivity), (4) low-efficiency mirror, that is, output coupler ( 95% reflectivity), (5) output laser beam. Components (3) and (4) form the optical cavity, also known as a Fabry-Perot interferometer. 

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