Pranab K. Mukhopadhyay

of TEM00 cw output at from Nd:CNGG laser end-pumped by a fiber-coupled diode laser array

Abstract In this paper we demonstrated and analyzed a high-power cw Nd:CNGG laser end-pumped by a fiber-coupled diode laser array in a convex–concave-type cavity. TEM00 mode output power of 1.63 W was obtained with 27% optical-to-optical conversion efficiency and slope efficiency of 44.5%. Thermal lensing and its variation with the incident pump power for this crystal have been measured. The coefficient for pump power induced diffraction losses of Nd:CNGG crystal have also been estimated for this laser configuration.

An alternative approach to determine the fractional heat load in solid state laser materials: application to diode-pumped Nd:YVO4 laser

Abstract A simple approach is described and used for on-line measurement of the fractional heat-load parameter ξ in an operating diode-pumped Nd:YVO4 laser at 1.06 μm wavelength for different doping concentrations. The method is based on the fact that if the thermo-optical properties of the sample are known then the ξ-parameter can be estimated from the measured effective focal length induced by the pump beam and any other lensing effect due to mechanical mounting of the sample for a given pumping configuration. The value of the fractional heat-load parameter estimated by our technique was in excellent agreement with the earlier reported values.

Experimental determination of effective stimulated emission cross-section in a diode pumped Nd:YVO4 micro-laser at 1064 nm with various doping concentrations

Abstract A practical method is described and used for determination of the effective stimulated emission cross-section ( σ e ) in an operating diode pumped Nd:YVO 4 micro-laser at 1064 nm with various doping concentrations. In this method a micro-laser is formed by keeping a small piece of the sample in a plane–plane resonator under semi-monolithic configuration and a fiber coupled diode laser ( 808 nm ) was used for pumping. The pump power induced thermal lensing effect was used to make the cavity stable. In thermally stabilized solid-state lasers the cavity parameters change dynamically with the pump power and hence the overlap integrals become a function of the absorbed pump power. In our method the overlap integrals were estimated by measuring the thermal lens focal length at the threshold. The value of σ e of Nd:YVO 4 crystal with different doping concentrations obtained by this method were in well agreement with the reported values.

A new approach to compute Overlap efficiency in axially pumped Solid State Lasers

In this work, we are reporting a new approach to compute the overlap efficiency of end pumped solid-state laser systems. Unlike existing methods in which the overlap integral is computed with a linearize approximation near the threshold, in this method the inverse of the overlap integral is computed numerically in the above threshold regime for several values of circulating fields. Now by fitting a linear curve to this data the overlap efficiency is obtained. The effect of the beam quality factor is also taken into account. It is demonstrated that the linearized approximation near the threshold can give rise to 50% error in overlap efficiency. The method was used to estimate the overlap efficiency in different types of axially pumped lasers.

Thermal lens measurement technique in end-pumped solid state lasers: Application to diode-pumped microchip lasers

A simple derivation, which relates the thermal lens focal length in solid state lasers to pump power and a method for direct estimation of thermal lens focal length, is reported. This method is applicable to any type of stable resonator. The method is used for the measurement of the thermal lens focal length with an accuracy of 8% in an axially pumped microchip laser. The variation of focal length with pump power is also measured.