1,720,965 research outputs found
Pulsed laser deposition of Yb:Y<sub>2</sub>O<sub>3</sub> planar waveguide lasers
No full textRare earth-doped sesquioxides, particularly yttria (Y2O3), scandia (Sc2O3) and lutetia (Lu2O3), are very promising materials for high power laser applications due to their excellent combination of thermal, optical and spectroscopic properties. These simple cubic crystals have been successfully doped with rare earth elements such as Yb, Tm and Er, but are challenging to grow as bulk crystals, due to their high melting points (~2400°C).Using pulsed laser deposition, we have grown both single and multilayer Yb-doped crystalline yttria waveguides on 1 cm2 YAG substrates. A multilayer sample with a 3 µm Y2O3 layer either side of a 6 µm Yb:Y2O3 doped region gave a maximum output power of 1.2 W at 1030 nm, for ~10.5 W of diode pump power. This waveguide design provides significantly higher gain for the fundamental waveguide mode than for higher order modes, enabling efficient multimode pumping whilst favouring diffraction limited output. The maximum observed slope efficiency was 22% (with respect to absorbed power), using a simple quasi-monolithic plane-plane resonator cavity with a 30%R output coupler. With no active cooling, even at these high pump powers, no sign of thermal effects in the waveguide have been observed, confirming the excellent thermal properties of this material.We will discuss these first results together with further experiments that will be performed with an optimised cavity length to achieve higher output power, lower threshold and greater slope efficiency
Doped sesquioxide growth by pulsed laser deposition for planar waveguide lasing applications
No full textSesquioxides, particularly yttria (Y2O3), lutetia (Lu2O3) and scandia (Sc2O3), are promising host materials for high power laser applications due to their high thermal conductivities, damage thesholds and their ability to incorporate a range of rare earth elements [1]; here we are focussing on thulium (Tm) and ytterbium (Yb) as our dopants. We have demonstrated thin film growth of doped sesquioxides by pulsed laser deposition as both single layers and cladded multilayers, and their ability to act as waveguides. Growth conditions are optimised by analysis of film crystallinity and presence of particulates. Highly crystalline films with low particulate counts are then put through waveguide characterisation and lasing experiments. Our work includes the growth of a 12µm-thick crystalline thulium doped yttria waveguide on a YAG substrate that, when pumped with a maximum of 600mW at 797nm, lased with an output of 35mW at 1.95µm, with 9% slope efficiency; this is the first example of such thin film Tm:yttria lasing to our knowledge. We will discuss these results and report progress towards higher power lasing by growth of lower loss cladded multilayer structures and thicker films (>30µm), suitable for diode pumping
1.2 W Yb:Y<sub>2</sub>O<sub>3</sub> planar waveguide laser
No full textA 12µm thick composite Yb-doped and undoped yttria layer is grown on a YAG substrate by pulsed laser deposition. For 8.5W of incident laser diode pump power the waveguide laser emits 1.2W at 1030nm
Crystal planar waveguides, a power scaling architecture for low-gain transitions
No full textIn this paper we present the underlying advantages that make the crystalline planar waveguide (PW) the key ingredient in power-scaling difficult or "weak" laser transitions, especially those which are extremely challenging to operate in other gain medium configurations. The planar waveguide architecture is shown to enable efficient laser operation of low-gain and/or quasi-four-level transitions that suffer reabsorption losses. Exemplar configurations are reported to make this case, for example, 1.4 W at 1.8 µm from a Nd:YAG double-clad planar waveguide laser (PWL), in addition to 0.5 W at 2.7 µm from a similar highly doped Er:YAG PWL. New laser performance levels from sesquioxide PWs fabricated by pulsed laser deposition are also presented for the first time, with >1 W obtained from a Yb:Y2O3 PWL. Current performance and future prospects are discussed for this laser architecture
Multi-beam pulsed laser deposition for advanced thin-film optical waveguides
No full textWe discuss our progress in the use of multiple laser beams and multiple targets for the pulsed laser deposition of thin films for waveguide laser and magneto-optic applications. In contrast to the more widely used single-beam/single-target geometries, having more than one laser-produced plume can allow tuning of the material properties and complex engineering of the deposited thin films. For optical applications - the majority of the work reported here - dopants can be selectively introduced, lattice mismatch and residual strain can be compensated, which is an important factor for successful growth of thin films of ~ tens of microns thickness, and refractive index values can be adjusted for fabrication of sophisticated waveguiding structures. We discuss mixed, layered, superlattice and Bragg reflector growth, which involve out-of-plane engineering of the film structure, and in-plane engineered geometries for designs relevant to thin-film disc lasing devices. Finally we briefly discuss our most recent use of multi-plume growth for magneto-optic thin films, which involves compositional tuning of final magnetic properties
PLD-grown Yb:Y<sub>2</sub>O<sub>3</sub> waveguide laser Q-switched by a graphene saturable absorber
No full textIn this paper, we present an Yb3+-doped Y2O3 waveguide laser fabricated by pulsed laser deposition (PLD) that is Q-switched using a mono-layer graphene saturable absorber
Yb:YAG planar waveguide lasers grown by pulsed laser deposition: 70% slope efficiencies at 16 W of output power
No full textWe present our recent advances in the use of pulsed laser deposition (PLD) to fabricate active gain elements for use as amplifiers and laser oscillators. Record output powers exceeding 16 W and slope efficiencies of 70% are reported for optimized epitaxial growth of Yb(7.5%):YAG on to YAG substrates. We show for the first time that the performance of PLD material can meet or even exceed that of materials grown by more established methods such as the Czochralski technique. Details of fabrication, characterization and laser performance are presented in addition to outlining expected future improvements
Pulsed laser deposition of thin films for optical and lasing waveguides (including tricks, tips and techniques to maximize the chances of growing what you actually want)
No full textIn the last 20-25 years, the technique of pulsed laser deposition (PLD) has emerged as a versatile, relatively fast and conceptually simple technique for growing a range of thin films of essentially any material. And while it is true that you will almost always grow something for your efforts, trying to optimise PLD so that what you grow is what you intended to grow is a different matter entirely. In this talk, I will use the growth of thin film doped crystalline materials that we are using as lasing waveguide structures as an example of how to tame the PLD process to produce high quality films that can match bulk crystal samples in terms of their final lasing performance. I will cover the technical aspects of substrate heating, particulate removal strategies, layer uniformity and crystal quality, and then move onto more advanced concepts such as single target versus multitarget geometries, mixed, layered, superlattice and Bragg structures and finally growth of ‘polo’ crystals, that have selected dopants only in the centre of the film, for application as thin disc lasers
Comparative study of rare-earth doped sesquioxides grown by pulsed laser deposition and their performance as planar waveguide lasers
No full textThe sesquioxides yttria, scandia and lutetia have been identified as promising host materials for high power lasers due to their excellent thermal properties, their ability to incorporate RE-ions and their resulting spectroscopic properties [1]. However, the melting points of these materials exceed 2400°C and are therefore problematic to grow from the melt. Pulsed laser deposition (PLD) is an alternative method of growing thin crystalline films of these materials, avoiding the requirement for such high temperature growth
7W diode-end-pumped PLD-grown Yb:Lu<sub>2</sub>O<sub>3</sub> planar waveguide laser
No full textAn Yb:Lu2O3 planar waveguide laser fabricated by pulsed laser deposition has reached an output power in excess of 7W, with a slope efficiency of 38%, end-pumped by a diode bar
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