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Valedictory Lecture by David Hanna University of Southampton November 9 2007

Valedictory Lecture by David Hanna University of Southampton November 9 2007. Vale!. The Fighting Temeraire, tugged to her Last Berth to be broken up, 1838 J.M.W.Turner. Theodore "Ted" Maiman (1927-2007). From Big Bang to the LASER: some historical highlights. Years ago

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Valedictory Lecture by David Hanna University of Southampton November 9 2007

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

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

  3. Theodore "Ted" Maiman (1927-2007)

  4. From Big Bang to the LASER: some historical highlights Years ago • Big Bang 13.7±0.2 Gyr • First stars 12.5 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

  5. From Big Bang to the LASER: some historical highlights Years ago • Big Bang 13.7±0.2 Gyr • First stars 12.5 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

  6. Astronomers & physicists grapple with the nature of light Rømer 1676 Observing Jupiter’s moons, revealed light to have finite velocity Young 1801 Measured light wavelength; calculated frequency n Maxwell 1862 Electromagnetism: LIGHT is an electromagnetic wave Planck 1900 Birth of quantum theory Einstein 1905 Special theory of relativity, based on invariance of “c” 1905 Postulated particle of light, of energy hn 1916 Introduced the process of stimulated emission Maiman 1960 Created first laser light

  7. Astronomers & physicists grapple with the nature of light Rømer 1676 Observing Jupiter’s moons, revealed light to have finite velocity Young 1801 Measured light wavelength; calculated frequency n Maxwell 1862 Electromagnetism: LIGHT is an electromagnetic wave Planck 1900 Birth of quantum theory Einstein 1905 Special theory of relativity, based on invariance of “c” 1905 Postulated particle of light, of energy hn 1916 Introduced the process of stimulated emission Maiman 1960 Created first laser light

  8. Ole Rømer (1644-1710) Speed of light measurement 1676

  9. Astronomers & physicists grapple with the nature of light Rømer 1676 Observing Jupiter’s moons, revealed light to have finite velocity Young 1801 Measured light wavelength; calculated frequency n Maxwell 1862 Electromagnetism: LIGHT is an electromagnetic wave Planck 1900 Birth of quantum theory Einstein 1905 Special theory of relativity, based on invariance of “c” 1905 Postulated particle of light, of energy hn 1916 Introduced the process of stimulated emission Maiman 1960 Created first laser light

  10. Thomas Young (1773-1829) On the Theory of Light and Colours Double slit experiment 1801 Philosophical Transactions of the Royal Society of London Vol92(1802) 12-48

  11. wavelength frequency velocity

  12. Thomas Young (1773-1829) On the Theory of Light and Colours Double slit experiment 1801 Philosophical Transactions of the Royal Society of London Vol92(1802) 12-48 “The absolute frequency expressed in numbers is too great to be distinctly conceived...”

  13. Velocity of light, and the metre Measure l and f: hence calculate velocity of light In 1983 cdefined as 299792458 m/s Metre defined as distance travelled by light in vacuum in 1/299792458 seconds “...and let’s all go home early” John Hall

  14. Astronomers & physicists grapple with the nature of light Rømer 1676 Observing Jupiter’s moons, revealed light to have finite velocity Young 1801 Measured light wavelength; calculated frequency n Maxwell 1862 Electromagnetism: LIGHT is electromagnetic wave Planck 1900 Birth of quantum theory Einstein 1905 Special theory of relativity, based on invariance of “c” 1905 Postulated particle of light, of energy hn 1916 Introduced the process of stimulated emission Maiman 1960 Created first laser light

  15. James Clerk Maxwell (1831-1879) • War es ein Gott, der diese Zeichen schrieb? • (Was it a god who wrote these signs?) • Boltzmann, 1891, quoting from Goethe’s Faust

  16. Heinrich Rudolf Hertz (1857 - 1894)

  17. Astronomers & physicists grapple with the nature of light Rømer 1676 Observing Jupiter’s moons, revealed light to have finite velocity Young 1801 Measured light wavelength; calculated frequency n Maxwell 1862 Electromagnetism: LIGHT is an electromagnetic wave. Planck 1900 Birth of quantum theory Einstein 1905 Special theory of relativity, based on invariance of “c” 1905 Postulated particle of light, of energy hn 1916 Introduced the process of stimulated emission Maiman 1960 Created first laser light

  18. Max Planck (1858-1947) “Black-body” radiation law

  19. Astronomers & physicists grapple with the nature of light Rømer 1676 Observing Jupiter’s moons, revealed light to have finite velocity Young 1801 Measured light wavelength; calculated frequency n Maxwell 1862 Electromagnetism: LIGHT is an electromagnetic wave Planck 1900 Birth of quantum theory Einstein 1905 Special theory of relativity,based on invariance of “c” 1905 Postulated particle of light, of energy hn 1916 Introduced the process of stimulated emission Maiman 1960 Created first laser light

  20. Albert Einstein (1879-1955)

  21. Astronomers & physicists grapple with the nature of light Rømer 1676 Observing Jupiter’s moons, revealed light to have finite velocity Young 1801 Measured light wavelength; calculated frequency n Maxwell 1862 Electromagnetism: LIGHT is an electromagnetic wave Planck 1900 Birth of quantum theory Einstein 1905 Special theory of relativity, based on invariance of “c” 1905 Postulated particle of light, of energy hn 1916 Introduced the process of stimulated emission Maiman 1960 Created first laser light

  22. Amplification by stimulated emission Photon energy hn = E2 – E1 Energy E2 Absorption Energy E1 Spontaneous emission Stimulated emission Emitted photon identical to incident photon: AMPLIFICATION OF LIGHT

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

  24. Theodore "Ted" Maiman (1927-2007)

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

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

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

  28. Brightness of some typical sources W/m2/sr Tungsten lamp, visible light 50W diode bar 1mW laser pointer 1W Ar laser (488nm) 1kW laser @1µm 1MW laser @1µm 30fs, 1mJ @0.8µm 45TW @0.8µm 105 1010 3 x 109 4.5 x 1012 1015 1018 5 x 1022 7 x 1025 * * * * * * * assumed diffraction limited

  29. Coherent X-ray generation

  30. The birth of nonlinear optics Peter Alden Franken (1928-1999) Laser field E is strong enough to modify response of medium LASER ω SECOND HARMONIC 2ω (Red) (UV) Quartz Response aE + bE2 + cE3 + … Nonlinear response

  31. One minute guide toOptical Parametric Amplification ω Frequencies ω1, ω2 are tunable, but always add up to ω3 Second harmonic generation 2ω ω ω1 ω3 = ω1 + ω2 Sum frequency generation ω2 Parametric generation and AMPLIFICATION ω1 ω3 ω2 ω1, ω2 are amplified in presence of strong pump field at frequency ω3 Any pair ω1, ω2 that add to ω3 can be amplified OPTICAL PARAMETRIC OSCILLATOR ω1 ω3 ω2

  32. The laser: ‘a solution in search of a problem’! • 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: $1012 global market by 2015

  33. The laser: ‘a solution in search of a problem’! • Optical communications • Military/defence • Machine tool control • Isotope separation • Surveying, ranging, LIDAR, Doppler speed monitoring • Security, forensic • Laser fusion, energy • Cytometry • Optical communications

  34. Semiconductor diode laser

  35. 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 Optical materials and structures

  36. 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

  37. Fast flash photography

  38. 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/THz Shortest pulse (as of 2007), ~80 as

  39. Electric field of optical pulsedisplayed on an “attosecond oscilloscope”

  40. Laser fusion - Nova

  41. Petawatt lasers

  42. Gravity wave observatory – Virgo F1

  43. LISA

  44. Laser guide star

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