Amplified luminescence and generation dynamics of the diode pumped erbium-ytterbium laser

Abstract

The influence of the cavity trapped amplified luminescence (CTAL) on the threshold, power and dynamic characteristics of Er, Yb : glass lasers with end and side diode pump configurations has been studied. The CTAL loss coefficient has been evaluated using the luminescence balance equation. The inverse proportion dependence of the CTAL loss coefficient on the cavity length has been revealed. It has been shown that amplification of luminescence in the laser cavity leads to a significant increase of the threshold pump power (∼3-5 times). The Er, Yb : glass laser generation dynamics has been modelled taking into account the luminescence evolution beginning with the onset of the diode pumping pulse. Depending on the diode pumping pulse amplitude, the increase or decrease of the Er, Yb : glass laser pulse generation delay can be observed.

Amplified spontaneous emission induced peculiarities of the passively Q-switched diode pumped erbium laser dynamics

“…At that, the behaviour of the curves 1 and 2 remains the same. These results are in agreement with [12] where it has been shown that amplified spontaneous emission can both increase and decrease the laser turn-on time depending on the pumping and cavity characteristics. The dependences of the pulse delay on the active element length at different ξ factors and fixed cavity length L = 100 mm are shown in Fig.…”

“…Active medium ytterbium and erbium doping concentrations were selected to be 4·10 27 and 5·10 25 m −3 , respectively. Yb, Er:glass and Co:MgAl 2 O 4 passive Q-switch parameters were taken from [12] and [16] respectively. Two-side transverse pumping of the cylindrical glass active element was assumed.…”

“…The conditions of the lasing and ASE radiation evolution differ in spontaneous emission factors δ las , δ ASE and loss coefficients k las , k ASE . Values of these factors were selected to be δ las = 0.001, δ ASE = 0.38 [12]. The loss coefficient k las magnitude was calculated using a standard approach [15] applied for the laser cavity under investigation.…”

“…The loss coefficient k las magnitude was calculated using a standard approach [15] applied for the laser cavity under investigation. ASE cavity loss coefficient k ASE was determined according to the technique based on the analysis of radiation distribution over the laser cavity and the luminescence balance equation written for steady-state conditions [12].…”

“…There are many effects, for example, laser media thermalization, slow Q-switching, effects of absorber lifetime, considered during the numerical modelling of passively Q-switched laser operation [7,8]. Amplified spontaneous emission (ASE), often referred to as amplified luminescence, is one of the factors that can affect significantly the laser threshold, power, and temporal characteristics [9][10][11][12]. However, the role of amplified spontaneous emission in dynamics of the passively Q-switched solid-state lasers is not determined properly.…”