Nd:Al2O3 as a gain material for integrated devices

Integrated optics, by which optical devices are fabricated on a chip, is really a speedily growing field. Integrated optics is different from free-space optics in the manner which performs that will usually need bulky equipment in free-space optics, are put together on one chip. Light is confined within on-chip lightguides, called ‘channel waveguides’. The idea of guiding optical signals in lightguides is well known ever since the early sixties. It wasn’t until the late sixties and early seventies, nonetheless, that the significance of integrated optics was realized, resulting in the initial topical meeting on integrated optics in 1972. Low-cost optical fibers developed in the early 1980’s have resulted in gradual replacement of metallic wires for telecommunication. In the meantime, improvements in micro and nanolithography technology triggered the development of integrated on-chip optical circuits. Integrated optical circuits have numerous applications in communications and sensing. Particularly, Neodymium-doped (Nd) materials have applications….

1 Introduction
1.1 Integrated optics and its applications
1.2 Integrated optical circuits
1.3 Al2O3, a promising material for integrated optics
1.4 Overview of this thesis
2 Gain in Nd:Al2O3
2.1 Introduction
2.2 Theory
2.2.1 The Nd ion
2.2.2 Level populations in thermal equilibrium
2.2.3 Absorption and stimulated emission
2.2.4 Small signal gain
2.3 Experimental setup
2.4 Simulations
2.4.1 Free-space to channel-mode overlap
2.5 Experimental results
2.6 Conclusions
3 Nd as a laser ion
3.1 Introduction
3.2 Laser theory
3.2.1 Radiative and non-radiative emission
3.2.2 Secondary processes
3.2.3 Rate equations
3.2.4 The laser cavity
3.2.5 Laser threshold
3.3 Simulation of Nd-doped Al2O3 lasers
3.4 Simulation results
3.5 Conclusions
4 Waveguides and couplers
4.1 Introduction
4.2 Theory
4.2.1 Waveguides
4.2.2 Directional coupler
4.2.3 Mach-Zehnder coupler (or balanced coupler)
4.3 Simulations
4.3.1 Simulation procedure and software
4.3.2 Waveguide mode analysis and calculations
4.3.3 Couplers
4.4 Experimental setup
4.4.1 Coupler measurements
4.4.2 SEM imaging
4.5 Results
4.5.1 Coupler measurements
4.5.2 Coupler SEM analysis
4.6 Conclusions
5 Integrated optical re
ectors for waveguide lasers
5.1 Introduction
5.2 Theory
5.2.1 Bend losses
5.2.2 Passive mirrors
5.2.3 The Sagnac mirror
5.3 Simulations
5.3.1 Bend losses
5.3.2 Sagnac mirror
5.4 Conclusions
6 Design of on-chip laser devices
6.1 Introduction
6.2 Exploring di erent laser designs
6.2.1 Sagnac-pumped integrated waveguide laser
6.2.2 Cavity-pumped integrated waveguide laser….

Source: University of Twente

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