Scaling laws of disk lasers

Abstract

a b s t r a c t Limit of power from amplified spontaneous emission (ASE), round-trip loss, and overheating is considered within simple model. The optimization of the output power with respect to size of the pumped region, its thickness and round-trip gain leads to the scaling laws for these parameters. In vicinity of the limit of power scaling, the round-trip loss should scale inversely proportional to the cubic root of the desired output power. This prediction agrees with the experimental data. The use of the thick undoped layer (anti-ASE cap) allows to increase for an order of magnitude the maximal power achievable at the same round-trip loss.

ASE and parasitic lasing in thin disk laser with anti-ASE cap

“…ASE problem in any inverted medium is the subject of intense research since the invention of the laser [5,6], and to avoid the severe impact of ASE and PL, many technical approaches have been proposed such as an anti-ASE cap [7][8][9], ASE absorber [10,11], and edge-face tilting [12]. Particularly, the anti-ASE cap, made from a transparent material, prevents the trapping of Spontaneous Emission (SE) inside the laser gain layer and suppresses the ASE effect increasing the maximum output power [13].…”

Storage of Energy in Disk‐Shaped Laser Materials

“…Then, its effect on the excitation can be taken into account with scaling of the effective lifetime τ that becomes τ exp(−GS), where G is gain and S is some effective path of ASE in the gain medium. Following [4][5][6], assume that the effective path S is of order of half of the maximal path of ASE in the medium. More optimistic estimate for S (quarter of the maximal path) is suggested in the comment [10], but the correction coefficient is not yet justified.…”

“…The maximal mean power of pump, that can be delivered to the active slab, is proportional to the area and inverse proportional to its thickness. The coefficient R of proportionality is the thermal loading parameter [4][5][6]:…”

“…Such a scaling law is an analogy of the scaling law by [13], that considered the optimization of maximal energy per active element for the case when the concentration of active centers is fixed. The similar law of power scaling for CW operation is considered in [4][5][6]; for that case, for the efficient operation, the background loss should scale down inversely proportional to the cubic root of the desired output power. We should greatly appreciate the confirmation of the scaling laws both for pulsed and the CW disk lasers with detailed numerical simulations and/or direct experiments.…”

“…For the continuous-wave disk lasers, roughly, at the power scaling, the loss should be reduced inversely proportional to the cubic root of the desired power [4][5][6]. For power scaling at fixed value of the background loss, the heat should be drained in the direction orthogonal to the propagation of the laser beam ( Figure 2); then other mechanisms (perhaps, deformation of wave front due to nonlinear refraction) may become dominant.…”