Lecture I Solid State Laser Ruby Laser
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This lecture briefly describes the construction and working of the Ruby LASER, the first laser system.
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Ruby laser
The document describes the components and operation of a ruby laser, which was the first successful laser developed by Maiman in 1960 and consists of a cylindrical ruby rod surrounded by a flash tube that optically pumps the rod. The ruby rod contains chromium ions that are excited to a higher energy level by the flash tube and achieve population inversion, leading to stimulated emission and the production of coherent laser light pulses at 694.3nm wavelength through a process of photon reflection and stimulated emission within the rod. Key characteristics of the ruby laser output include monochromaticity, directionality, spatial and temporal coherence, and brightness.
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A He-Ne laser produces coherent red light through stimulated emission. It works by electrically exciting a gas mixture of helium and neon atoms. Energy from excited helium atoms is transferred to neon atoms, producing population inversion between neon energy levels. When excited neon atoms drop to a lower energy level, they emit photons of 632.8 nm wavelength that stimulate additional photon emissions, producing a coherent laser beam. He-Ne lasers operate continuously and are commonly used for applications like barcode scanning and holography due to their low cost and narrow visible beam.
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The document describes the components and operation of a ruby laser, which was the first successful laser developed by Maiman in 1960 and consists of a cylindrical ruby rod surrounded by a flash tube that optically pumps the rod. The ruby rod contains chromium ions that are excited to a higher energy level by the flash tube and achieve population inversion, leading to stimulated emission and the production of coherent laser light pulses at 694.3nm wavelength through a process of photon reflection and stimulated emission within the rod. Key characteristics of the ruby laser output include monochromaticity, directionality, spatial and temporal coherence, and brightness.
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- The basic components and functioning of a laser, including the active medium, excitation mechanism, and optical resonator.
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A He-Ne laser produces coherent red light through stimulated emission. It works by electrically exciting a gas mixture of helium and neon atoms. Energy from excited helium atoms is transferred to neon atoms, producing population inversion between neon energy levels. When excited neon atoms drop to a lower energy level, they emit photons of 632.8 nm wavelength that stimulate additional photon emissions, producing a coherent laser beam. He-Ne lasers operate continuously and are commonly used for applications like barcode scanning and holography due to their low cost and narrow visible beam.
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The document describes the ruby laser, which was the first laser invented in 1960 by Theodore Maiman. It uses a synthetic ruby crystal as the gain medium, which contains chromium atoms that absorb green and blue light and emit red light. The ruby laser produces pulsed red light at 694.3 nm. It works based on three energy levels of the chromium atoms in the ruby crystal. When pumped by a flash lamp, the atoms are excited to higher energy levels and undergo stimulated emission, producing coherent laser light. Ruby lasers were used for applications like holography and laser surgery, but have been replaced by better solid-state lasers due to low efficiency and pulsed output.
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A nitrogen laser operates by using molecular nitrogen as its gain medium, emitting ultraviolet light with a wavelength of 337.1 nm. When an electric spark excites nitrogen atoms, stimulated emission produces a laser beam. Nitrogen lasers have a short pulse width and high intensity, drawing high power through electrical discharge. They can be used for applications like laser-induced fluorescence, photochemistry, spectroscopy, and pumping dye lasers.
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Schlossberg - Lasers and Optics - Spring Review 2013
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Lecture I Solid State Laser Ruby Laser
- 1. By Dr. Arpana Agrawal Assistant Professor Department of Physics (For Master’s students) Shri Neelkantheshwar Government PostGraduate College, Khandwa, India UNIT III: Types of LASERS
- 2. Types of LASERS: Introduction On the basis of Active medium -depending on the state of active medium -(solid/liquid/gas) On the basis of mode of operation -Continuous wave mode (CW) -Pulsed mode On the basis of laser levels -3-level laser system -4-level laser system
- 3. Types of LASERS on the basis of active medium Solid State lasers: Active medium-Solid form eg. Ruby laser; Nd:YAG laser etc Gas lasers: Active medium-Gaseous form e.g. He-Ne laser; Carbon-di-oxide (CO2) laser etc Liquid lasers: Active medium-Liquid form e.g. Dye lasers-Rhodamine laser; Polymethene laser etc Semiconductor lasers: Active medium-Semiconductors e.g. GaAs laser; InP laseretc. Chemical lasers: based on chemical reactions e.g. HCl; HF etc. Types of LASERS: Introduction
- 4. Lecture I: Solid state laser: Ruby laser Lecture II: Solid state laser: Nd:YAG laser Lecture III: Gas laser: He-Ne laser Lecture IV: Gas laser: CO2 laser Lecture V: Semiconductor laser: GaAs Lecture VI: Liquid/Dye lasers Lecture VII: Chemical lasers: HCl and HF Lecture VIII: Summary (Recapitulation of UNIT IV) Content of UNIT-IV
- 5. Lecture I: Solid state laser: Ruby laser Topics to be covered under Lecture I • Introduction and Construction -Active medium -Pumping method -Optical resonator • Working: Energy level diagram • Advantage and Disadvantages of Ruby LASER • Applications • Summary
- 6. Ruby rod Xenon flash tube Laser (Coherent) (694.3 nm) M2 M1 Electrode Electrode Power supply Solid-state laser, three-level laser system, and first laser invented and operated by Theodore H Maiman at Hughes Research Laboratories on 16th May 1960 Cross-sectional view Construction -Active medium: Single crystal of Al2O3:Cr3+ in the form of cylindrical rod -Pumping method: Optical pumping using Xenon flash lamp (Helical); rolled over ruby rod -Optical resonator: Ends of the ruby rod are kept in between two optically coated mirrors, silvered differently. Introduction and Construction M1: Fully reflecting mirror (100%); M2: Partially reflecting mirror (99%)
- 7. Metastable state (10-3 sec) Ground state (10-8 sec) Excited state (4F1) Excited state (4F2) Laser Output (red ; 694.3 nm) Working: Energy level diagram of Cr3+ ions in Ruby Pumping region Laser transition 400λ(nm)500600700
- 8. Disadvantages • The laser requires high pumping power because the laser transition terminates at the ground state and more than half of ground state atoms must be pumped to higher state to achieve population inversion. • The efficiency of ruby laser is very low because only green component of the pumping light is used while the rest of components are left unused. • The laser output is not continuous but occurs in the form of pulses of microseconds duration. • The defects due to crystalline imperfection are also present in this laser. Advantages- • Ruby lasers are economical. • Construction and function of ruby laser is self explanatory. Advantages and Disadvantages of Ruby LASER
- 9. • Ruby lasers have declined in use with the discovery of better lasing media. They are still used in a number of applications where short pulses of red light are required. • Low output power, so are used as toys for children. • Used in schools, colleges, universities for science programs. • Used as decoration piece & artistic display. • Holographers around the world produce holographic portraits with ruby lasers, in sizes up to a metre squared. • Many non-destructive testing labs use ruby lasers to create holograms of large objects such as aircraft tires to look for weaknesses in the lining. • Ruby lasers were used extensively in tattoo and hair removal Applications
- 10. Summary Type Solid state laser; Three- level laser system Active medium Ruby rod (Cr: Al2O3) Active centre Cr3+ ion Pumping method Optical pumping Pumping source Helical flash lamp of filled with Xenon Optical resonator The ends of the ruby rod are kept in between two optically coated mirrors, silvered differently. Output power Low Nature of the output Pulsed (Spiked) Wavelength emitted 693.4 nm Summary Thank you Lecture II-to be contd…