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The solid-state laser - A 50 year old light bulb. Fredrik Laurell, Laser Physics group, Applied Physics Department, KTH. Lasers - in the Solid State. What ? How ? Where and why ?. Outline. Outline. Background and history Diode laser concepts Compact stable tailored lasers
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The solid-state laser - A 50 year old light bulb Fredrik Laurell, Laser Physics group, Applied Physics Department, KTH
Lasers - in the Solid State • What ? • How ? • Where and why ?
Outline Outline • Background and history • Diode laser concepts • Compact stable tailored lasers • Diode-pumped Solid-state Lasers • Fiber lasers • Tailoring DPSSL and fiber lasers • Conclusions
Basic Laser • Laser medium • Resonator • Pump Atoms in a matrix Energy diagram for a laser stimulated emission
Laser history • Einstein introduces quantum transitions • 1924 Tolman suggests amplification via stimulated emission • 1920- 50 Quantum mechanics, atomic and microwave physics • 1954 first MASER • 1959 acronym LASER was introduced • Schawlow: ”ruby is not a good laser candidate” • 1960 Maiman realize the ruby laser it is a very unlikely process
a ruby rod, mirros deposited on the end-faces and a flash lamp Maiman had to fabricate everything himself Absorption and emission for Cr3+
Gas lasers Dye lasers Solid-state lasers; Ruby, Nd:YAG, Ti-Sapphire Diode-pumped solid-state lasers Thin disc laser Fiber laser Semiconductor laser Free electron lasers ... What lasers do we have today?
Choosing the Laser Medium Finding the right atom and matrix bySpectroscopy 1. Absorption 2. Emission/ Fluorescence 3. Lifetime of energy levels • Gas • Liquid • Solids Crystals Semiconductor Glass Fiber Dye in gelatin ...
Laser History - continued • 60-ties laser invented and most effects discovered • 70-ties a solution looking for a problem ... • 80-ties problems discovered! • 90-ties commercial success!! • 00-ties everybodies toy!!! • Diode Pumped Solid-state lasers (DPSSL) • Fiber lasers • Diode lasers
The diode laser the smallest and most frequently used laser The diode laser and the optical fiber is the backbone of telecommunication Nobel prize 2000 Zhores I. AlferovA.F. Ioffe Physico-Technical Institute, St. Petersburg
Types of diode lasers • Edge emitters • Array lasers • Broad area diodes • Tapered diodes
Types of diode lasers -continued • VECSELs – OPSL A vertical-external-cavity surface-emitting-laser (VECSEL) is a small semiconductor laser similar to a vertical-cavity surface-emitting laser (VCSEL).
Solving the spectral problem Grating stabilization – feed-back Fiber Bragg Gratings Diffraction gratings Volume Bragg Gratings Integrated gratings
Tuning the diode – alternative feed-back techniques Stretching the FBG Temperature tune or translating a chirped VBG Retroreflector = continuous tuning
Diode laser tuning with strechable silicone grating Moulded silicone grating Littrow configuration O2 sensing in air Laser tunable over 3 nm S Bertani, B Jacobsson, F Laurell, V Pasiskevicius and M Stjernström, Opt. Express, 14, 11982, 2006.
Increasing the Power- Resonant Cavities Resonant cavities require advanced locking techniques W. Risk, Compact Blue-Green Lasers
The Diode-Pumped Solid-State Laser Converts a poor diode laser beam to a high quality solid-state laser beam - spatially, spectrally and temporally engineered Solid- State Material Functional element Diode Pump Allows functionality to be integrated in the laser
heat laser pump DPSSL scales to highpower Minimize the quantum defect – i.e. heat