Mirror laser cavity output coupler

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. 

The dye laser was fully optimized for these fundamental tuning curves, making the available input power be the limit to the output reached. With the weaker pump lines, the radius of the fold mirror (Ml of Fig. 10) was decreased to tighten the dye and matching pump focal areas and keep the gain well above the 2.5% s.f. cavity losses. (The 10-cm radius for the red dyes became 7.5 cm for the stilbenes, coumarins, and S9M, and 5.0 cm for IR140). The transmission of the output coupler was also optimized across the span of each dye (the breaks on several of the tuning curves are places where a different output coupler was... 

For example, contemplate a laser cavity system with the following characteristics reflectivity of the HR mirror 7 i = 0.998 reflectivity of the output coupler R = 0.958 round-trip loss (excluding mirror loss) Lrt = 0.08 amplifier gain Ga = 1.05. Using these values in Equation (3.2) one obtains Gl = 1.045 this is a typical value encountered for CW gas lasers near laser threshold (see Section 3.4). 

Fig. 2.5. Picosecond configuration of the folded titanium sapphire laser cavity. AOM acusto-optic modulator OC output coupler Pi, P2 pump mirrors Mi to Me cavity mirrors GTI Gires-Tournois interferometer (by courtesy of Spectra Physics)...

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