On the depolarisation of radiation of a transversely diode-laser-array-pumped Yb, Er-doped phosphate glass active element

Repetitively pulsed lasing in a Yb, Er-doped phosphate glass transversely pumped by a diode laser array is studied. Lasing on the lowest TEM₀₀ resonator mode is obtained both in the quasi-continuous regime with an output power of 4.1 W and in the passive Q-switching regime (23-ns, 1.2-mJ pulses). The depolarisation of linearly polarised radiation of a He – Ne laser transmitted through the phosphate glass active element (AE) along the resonator axis is investigated. The dependences of depolarisation on the AE heating and experimental conditions are determined. It is shown that radiation losses caused by its depolarisation can present problems in the development of lasers emitting at 1.5 μm, in which polarisers should be used (for example, regenerative amplifiers).