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Valedictory Lecture by David Hanna University of Southampton November 9 2007 Vale!

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Presentation on theme: "Valedictory Lecture by David Hanna University of Southampton November 9 2007 Vale!"— Presentation transcript:

1 Valedictory Lecture by David Hanna University of Southampton November Vale!

2 The Fighting Temeraire, tugged to her Last Berth to be broken up, 1838 J.M.W.Turner

3 Theodore "Ted" Maiman ( )

4 From Big Bang to the LASER: some historical highlights Years ago  Big Bang13.7±0.2 Gyr  First stars12.5 Gyr  Our sun (solar system) 4.5 Gyr  First life on earth 3.5 Gyr  Cambrian explosion (proper vision evolved) 530 Myr  Homo Sapiens evolved 100 kyr  Cave painters at work 30 kyr

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6 Years ago  Big Bang13.7±0.2 Gyr  First stars12.5 Gyr  Our sun (solar system) 4.5 Gyr  First life on earth 3.5 Gyr  Cambrian explosion (proper vision evolved) 530 Myr  Homo Sapiens evolved 100 kyr  Cave painters at work 30 kyr  Astronomers and physicists evolve From Big Bang to the LASER: some historical highlights

7 Astronomers & physicists grapple with the nature of light R ø mer 1676Observing Jupiter’s moons, revealed light to have finite velocity Young1801Measured light wavelength; calculated frequency Maxwell1862Electromagnetism: LIGHT is an electromagnetic wave Planck1900Birth of quantum theory Einstein1905Special theory of relativity, based on invariance of “c” 1905Postulated particle of light, of energy h 1916Introduced the process of stimulated emission Maiman1960Created first laser light

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10 Astronomers & physicists grapple with the nature of light R ø mer 1676Observing Jupiter’s moons, revealed light to have finite velocity Young1801Measured light wavelength; calculated frequency Maxwell1862Electromagnetism: LIGHT is an electromagnetic wave Planck1900Birth of quantum theory Einstein1905Special theory of relativity, based on invariance of “c” 1905Postulated particle of light, of energy h 1916Introduced the process of stimulated emission Maiman1960Created first laser light

11 Speed of light measurement 1676 Ole Rømer ( )

12 Astronomers & physicists grapple with the nature of light R ø mer 1676Observing Jupiter’s moons, revealed light to have finite velocity Young1801Measured light wavelength; calculated frequency Maxwell1862Electromagnetism: LIGHT is an electromagnetic wave Planck1900Birth of quantum theory Einstein1905Special theory of relativity, based on invariance of “c” 1905Postulated particle of light, of energy h 1916Introduced the process of stimulated emission Maiman1960Created first laser light

13 On the Theory of Light and Colours Philosophical Transactions of the Royal Society of London Vol92(1802) Double slit experiment 1801 Thomas Young ( )

14 wavelengthfrequencyvelocity

15 On the Theory of Light and Colours Philosophical Transactions of the Royal Society of London Vol92(1802) Double slit experiment 1801 Thomas Young ( ) “The absolute frequency expressed in numbers is too great to be distinctly conceived...”

16 Velocity of light, and the metre Measure and f: hence calculate velocity of light In 1983 c defined as m/s “...and let’s all go home early” John Hall Metre defined as distance travelled by light in vacuum in 1 / seconds

17 Astronomers & physicists grapple with the nature of light R ø mer 1676Observing Jupiter’s moons, revealed light to have finite velocity Young1801Measured light wavelength; calculated frequency Maxwell1862Electromagnetism: LIGHT is electromagnetic wave Planck1900Birth of quantum theory Einstein1905Special theory of relativity, based on invariance of “c” 1905Postulated particle of light, of energy h 1916Introduced the process of stimulated emission Maiman1960Created first laser light

18 James Clerk Maxwell ( ) War es ein Gott, der diese Zeichen schrieb? (Was it a god who wrote these signs?) Boltzmann, 1891, quoting from Goethe’s Faust

19 Heinrich Rudolf Hertz ( )

20 Astronomers & physicists grapple with the nature of light R ø mer 1676Observing Jupiter’s moons, revealed light to have finite velocity Young1801Measured light wavelength; calculated frequency Maxwell1862Electromagnetism: LIGHT is an electromagnetic wave. Planck1900Birth of quantum theory Einstein1905Special theory of relativity, based on invariance of “c” 1905Postulated particle of light, of energy h 1916Introduced the process of stimulated emission Maiman1960Created first laser light

21 Max Planck ( ) “Black-body” radiation law

22 R ø mer 1676Observing Jupiter’s moons, revealed light to have finite velocity Young1801Measured light wavelength; calculated frequency Maxwell1862Electromagnetism: LIGHT is an electromagnetic wave Planck1900Birth of quantum theory Einstein1905 Special theory of relativity, based on invariance of “c” 1905Postulated particle of light, of energy h 1916Introduced the process of stimulated emission Maiman1960Created first laser light Astronomers & physicists grapple with the nature of light

23 Albert Einstein ( )

24 Astronomers & physicists grapple with the nature of light R ø mer 1676Observing Jupiter’s moons, revealed light to have finite velocity Young1801Measured light wavelength; calculated frequency Maxwell1862Electromagnetism: LIGHT is an electromagnetic wave Planck1900Birth of quantum theory Einstein1905Special theory of relativity, based on invariance of “c” 1905Postulated particle of light, of energy h 1916Introduced the process of stimulated emission Maiman1960Created first laser light

25 Amplification by stimulated emission Energy E 2 Photon energy h = E 2 – E 1 Stimulated emission Absorption Energy E 1 Spontaneous emission AMPLIFICATION OF LIGHT Emitted photon identical to incident photon: AMPLIFICATION OF LIGHT

26 Nobel prize for physics 1964 “… maser-laser principle” Prokhorov, Townes and Basov

27 Theodore "Ted" Maiman ( )

28 Amplification of an input beam Amplification of spontaneous emitted light Amplification plus feedback: oscillation builds up a directional output - Laser Beam Laser oscillation Input

29 Taming the laser: the pursuit of perfection Temporal shaping Spectral filter to shape spectrum, eg to discriminate against unwanted frequencies Spatial filter to discriminate against excessive divergence Gain medium Mirror

30 Figures of merit for light sources Power Spectral ≡ Brightness [Diameter x divergence] 2 [Spectral Bandwidth] Power Brightness ≡ [Beam diameter x Beam divergence] 2

31 Brightness of some typical sources Tungsten lamp, visible light 50W diode bar 1mW laser pointer 1W Ar laser (488nm) 1kW 1MW 30fs, ************ x x x x W/m 2 /sr * assumed diffraction limited

32 Coherent X-ray generation

33 The birth of nonlinear optics Laser field E is strong enough to modify response of medium Nonlinear response Response aE + bE 2 + cE 3 + … Peter Alden Franken ( ) LASER ω Quartz SECOND HARMONIC 2ω (Red) (UV)

34 One minute guide to Optical Parametric Amplification Frequencies ω 1, ω 2 are tunable, but always add up to ω 3 Second harmonic generation Sum frequency generation Parametric generation and AMPLIFICATION ω 1, ω 2 are amplified in presence of strong pump field at frequency ω 3 Any pair ω 1, ω 2 that add to ω 3 can be amplified OPTICAL PARAMETRIC OSCILLATOR ω ω 2ω2ω ω1ω1 ω2ω2 ω 3 = ω 1 + ω 2 ω2ω2 ω3ω3 ω1ω1 ω2ω2 ω3ω3 ω1ω1

35  Cutting, drilling, welding, scribing, marking chip repair, printing, lithography  Laser gyros, sensors, pollution monitors, bar-code readers DVDs, displays, entertainment  Microscopy, surgery, corneal sculpting, optical coherence tomography Optoelectronics forecast: $10 12 global market by 2015 The laser: ‘a solution in search of a problem’!

36  Optical communications  Military/defence  Machine tool control  Isotope separation  Surveying, ranging, LIDAR, Doppler speed monitoring  Security, forensic  Laser fusion, energy  Cytometry  Optical communications

37 Semiconductor diode laser

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40 Optical materials and structures  Laser materials  Semiconductor laser, quantum wells, wires, dots  Nonlinear optical materials  Optical fibres, waveguides  Bragg gratings for fibre, waveguides, semiconductors  Photonic bandgap materials, holey fibres  Metamaterials  Negative refractive index materials  Liquid crystals  LEDs, polyLEDs

41 The laser as a scientific tool  Ultrafast time resolution  Laser fusion  Laser particle accelerator  Gravity wave observatory  Laser guide star for astronomy  Optical clocks, frequency standards  Quantum computing  Tests of QED, General relativity  Coherent control  Atom interferometry  Cold atoms, Bose-Einstein condensates

42 Fast flash photography

43 Short pulse generation with lasers Pulse of time duration T secs requires a spectral bandwidth of at least 1/ T Hz, hence also carrier frequency of at least 1/ T Hz Pulse durationRequired bandwidth s, 1ns (nanosecond) s, 1ps (picosecond) s 1fs (femtosecond) s, 1as (attosecond) 10 9 Hz, 1GHz (Gigahertz) Hz, 1THz (Terahertz) Hz, 1PHz (Petahertz) Hz, 1EHz (Exahertz) Shortest pulse (as of 2007), ~80 as

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45 Electric field of optical pulse displayed on an “attosecond oscilloscope”

46 Laser fusion - Nova

47 Petawatt lasers

48 Gravity wave observatory – Virgo F1

49 LISA

50 Laser guide star

51 Manipulation of atoms  Atom cooling, trapping, guiding  Bose-Einstein condensation  Atom interferometers  Coherent control of atoms

52 Coherent control of atoms Optical pulses Atom state Atom phase 1 2 |1 + a |2 |1 |2 |1

53 Kathleen Puech, Rudiger Paschotta, Paul Suni, Markus Pollnau, Dave Shepherd, David Cotter, Andy Clarkson, Richard Wyatt, Mike Percival, Ralf Koch, Sylvain Girard, Martin O’Connor, Helen Pask, Jose Sais, Michael Yuratich, Joseph Koo, Simon Mussett, Dave Arnold, Barry Luther-Davies, Vikram Rampal, Andy Turner, Richard Wyatt, Leslie Laycock, Pertti Karkkainen, Walter Tuttlebee, Craig Sawyers, Andy Berry, David Hearn, David Pratt, Ian Carr, Marco Pacheco, Ian Alcock, David Pointer, Ken Ure, Andrew Kazer, Leigh Bromley, Ian Perry, Andy Guy, Michael Ibison, Matthew McCarthy, Colin Mackechnie, Martin Milton, Tony Neilson, Stuart Butterworth, Valerio Pruneri, Kevin Martin, Paul Hardman, Christoph Bollig, Nick Moore, Graham Friel, Rob Hayward, Malcolm Watson, David Brink

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