Laser pumping

 

The green pump laser is a crucial component of the oscillator as it is the source of the initial photons that cascade through the system

Laser pumping is the act of energy transfer from an external source into the gain medium of a laser. The energy is absorbed in the medium, producing excited states in its atoms. When the number of particles in one excited state exceeds the number of particles in the ground state or a less-excited state, population inversion is achieved. In this condition, the mechanism of stimulated emission can take place and the medium can act as a laser or an optical amplifier. The pump power must be higher than the lasing threshold of the laser. (source wikipedia)

 

External laser pumping

A laser of a suitable type can be used to pump another laser. The pump laser's narrow spectrum gives it much more efficient energy transfer than flashlamps. Diode lasers pump solid state lasers and liquid dye lasers. A ring laser design is often used, especially in dye lasers. The ring laser uses three or more mirrors to reflect light in a circular path. This helps eliminate the standing wave generated by most Fabry–Pérot resonators, leading to a better use of the gain medium's energy. 

Source wikipedia

Ti-Sapphire pumping: “The green pump laser is a crucial component of the oscillator as it is the source of the initial photons that cascade through the system. The pump laser quality therefore has a direct correlation with the quality of the light exciting the Ti-Sa crystal and therefore the emitted light. A pump laser with excellent beam quality, good power stability and low amplitude noise, will result in more stable, low noise Ti:Sa output pulses. The pump laser has traditionally been an argon ion laser, but although they can achieve high power and beam quality, they are large, inefficient with relatively short lifetimes and high running costs.”

Moreover Ti-Sa crystal absorption is about 15% higher at 515nm than 532nm.

Ytterbium pumping : Ytterbium can be pumped at 915nm or 976nm. ALS is the only supplier on the market of high power single mode 976nm laser sources for this demanding application.

Crystal pumping: Some may want to pump other exotics crystal. The parameters of interests remain the same: power stability, pointing stability, low-noise, polarization stability and spatial mode quality and stability.

  ALS technological advantages

Power stability. Best on the market (< ±0,2% short term and < ±0,3% long term)

Thanks to its cooler less laser head, its fiber technology and its single pass frequency doubling process, the ALS lasers offer an excellent pointing stability and spatial mode quality/stability which are crucial parameters in laser pumping application.

Our low noise level is the reason why most of the users would be interested in ALS single frequency version.

Polarization stability: the user optical setup may include polarized optics and so the power stability may be degraded if the polarization stability is not good enough. ALS offer an extinction ratio >> 99,9% with polarization variation << 0,1%.

Popular  Laser versions

ALS-VISIBLE - 500mW to 2W@488nm, 10W515nm / 532nm – single frequency

ALS-IR - 5 to 10W @976nm – single frequency or narrow linewidth