RD-RI61 623 QUANTUN ELECTRONICS IN THE UK A NTIONL-SURVEY vCONFERENCE(U) OFFICE OF NAVAL RESEARCH LONDON (ENGLAND)

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Quantum Electronics in the UK: A National-Survey Conference

12 PERSONAL AL.1 HOR(S)Paul Roman

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'6 SUPPLEMENTARY NOTATION

71, !-O',ATI CODES 18 SUBjECT TERMS (Continue on reverse if necessary and identify by block number)PtD GROuP SUB GROUP -'Quantum Electronics, Quantum optics

20 05, 06 Lasers, -UwitedKidom-t ..

INonlinear optics Optoelectronics 6-'9 ABSTRACT (Continue on reverse if necessary and identify by block number)

The Seventh National Quapitum Electronics Conference met from 16 through 20 September1985 in Great Malvern, UK. This report highlights presentations on lasers, nonlinearoptics, and quantum optics.

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CONTENTS

Page

IINTRODUCTION....................................................................I1

2 SELECTED REVIEWS ....... ....... o................................ 1

Lasers..........................................................................1 iINonlinear Optics............................................................. 4Quantum Optics ............ ................................... 5

3 CONCLUDING REMWARKS........................................... ................... 6

APPENDIX: CONFERENCE PAPERS........... .......................................... . 7

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QUANTUM ELECTRONICS IN THE UNITED KING- * Electra-optics DevicesDOM: A NATIONAL-SURVEY CONFERENCE * Spectroscopy

e Miscellaneous Applications (two sea-1 INTRODUCTION sions)

The uantm Elctrnicsgrou ofIn this report I will only describethe Instit t m of ecPhysic (UK)p ha ostb some selected papers in the first, sec-

tihed ans ine tradhyiion every h second- ond, and third groups. The choice isyisear a Naional Qadint eernic on- primarily personal, but it partly also

yeara Ntioal uanum lecroncs on- reflects on the perceived quality. Theference is held in a peaceful location appendix gives a complete listing of allassociated with one of the active aca- oa rsnainwt ae n fdemic or governmental research centers oa rsnainwt ae n f

in tis iel ofresarc. Qantm eec- filiations of the authors. On request,inronis, p f om tseciQating contr- I shall be glad to supply individualbtons, toar ouro bas unersitaing o copies of the abstracts that werebte n fnatal purobscse n tboder-igo printed in the TechnicaZ Digest. I canlie f cassial andese quntm physics, also send a copy of the list and focallays ofas i an d evrinrasng rolesins interests of the 30 or so British exhib-

* defense, industry, and consumer serv- itor ho minandinomtvebohices. It is, therefore, fortunate that athemtiga rather informal, open, unhurried con- 2 SELECTED REVIEWSference framework exists where seniorscientists mix with a strong group of Lasersyounger researchers (mainly from univer- I think that the talks in thissities, but also from government re- group were the highlights of the confer-search centers and private industry), ence.and with a surprisingly large number of Techniques for generating ultra-graduate students, short optical pulses have, apparently,

The Seventh National Quantum Elec- continued to advance at a rapid rate.tronics Conference met from 16 through C.V. Shank (a visitor form AT&T Bell20 September 1985 at Great Malvern. It Laboratories, New Jersey) gave an in-was hosted by the Royal Signals and formative introduction to this area,Radar Establishment (RSRE), which has describing the generation of pulses asits laboratories in this area. Apart short as 8 femtoseconds, using passivefrom the Institute of Physics, the Royal mode locking and pulse compression.Society of Chemistry and the Institution Another line of development, described

* of Electrical Engineers (UK) provided in this talk, was the construction of asupport for the meeting. There were high repetition rate (10 kHz) amplifierabout 200 participants, almost exclu- that can maintain an energy in excess of

* sively from the UK and the Republic of I pJ with a 40-ps pulse width. In theIreland. There were 11 invited talks same area, A.S.L. Games (Imperial Col-and 50 contributed papers, all delivered lege) talked about work in the opticswithout haste (but limited to 30 and section concerned with subpicosecond

*15 minutes, respectively) in unsplit compression of laser pulses. They usedplenary sessions. Half of one day was a two-stage optical fiber/grating pairreserved to the viewing of 38 poster arrangement to compress by a factor ofpapers. There was sufficient time for 113 the 85-ps pulses from a continuous-both formal and informal discussions, wave mode locked Nd:Yag laser. The com-

*The talks were grouped into the pression technique has been used alsofollowing categories: for the Q-switched and mode-locked sys-

tem, achieving in this experiment higher*Lasers (four sessions) peak pulse powers.*Nonlinear Optics (two sessions) New solid state lasers were covered

* Quantum Optics (two sessions) by two talks. In the first, M.J.P. Payne

discussed work done with H.W. Evans at transitions may also be capible of laser

the RSRE on flashlamp pumped chromium action, including transitions in dopantsdoped gadolinium/scandium/gallium garnet which have not previously shown laserlasers which, as is now generally ac- action in a glass host. Other possibleknowledged, offer broadly tunable and applications include the use of fiberspotentially efficient high-power laser as amplifiers, reducing in such devicesaction. The researchers studied the problems of thermal distortion and frac-factors that limit performance. They ture. The Southampton scientists fabri-concluded that excited state absorption, cated the fibers by a modified chemicalcolor center formation, and thermal vapor deposition technique. They usedlensing in the lasing medium are the fused silica, with a core diameter ofmajor problems. Incidentally, they 4 Pm and Nd fon concentrations aroundfound that the low slope efficiency 300 ppm. In the experiments, end-pump-(0.02 percent), which was due primarily Ing with a Rhodamine 6G dye laser (and

- to high insertion loss and small lasing later a GaAs laser) was used. At thevolume, could be increased to over lasing wavelength of 1.088 jim, losses0.2 percent if one of the plane mirrors were less than 10 dB/km. Resonators havewas replaced by a concave one. been constructed either with mirrors

A second interesting talk on novel separated from the fiber ends with mi-solid state lasers, reporting on a coop- croscope objectives, or with mirrorseration between Payne and two colleagues butted against the fiber ends. With theat the University of Sheffield, address- former arrangement, a lasing thresholded the problem of tunable laser glasses. corresponding to a few milliwatts ofProbably it will turn out that working absorbed dye laser power was obtained.

- with glass is easier than with crystals. Continuous-wave, single-mode operationBut to produce a high yield, broad-band could easily be achieved. Current workfluorescent glass implies finding suita- focuses on broad tunability, mode lock-ble dopants (such as 3d or filled-shell ing, and the use of other dopants thations) and a chemically durable glass may lead to 5 um or longer wavelengthwith low refractive index and expansion radiation.

coefficient. The authors studied the There is some interest these dayseffects of glass composition, minor ad- in multi-wavelength operation of lasers.ditives, co-doping, furnace temperature, A good presentation in this area wasand annealing conditions. The main glass given by R.C. Hollins and D.L. Jordansystems chosen were soda lime silicates (RSRE) who described their work on si-

and variations, a fluoride glass, and a multaneous lasing of two or more ultra-calcium borophosphate glass. The main violet rare gas halide transitions.dopants were Cr3+, Mn2 + , Cu+ , with ref- They studied lasers with XeCl + XeF and

erence to Sn2+ , Pb2+ , Ti3+ . One conclu- with KrF + XeF mixtures. Efficient si-" sion of the study was that future im- multaneous lasing was demonstrated, and

provement in fluorescence yield and it was shown that the compatibility ofdecay profile may come from suppressing the different laser media depends criti-the dipole-dipole interaction. cally upon chemical stability of the gas

Single-mode neodymium fiber lasers mixture. Excitation transfer processesare also attractive, innovative, solid do not inhibit simultaneous laserstate devices, and research in this di- action.rection was reported by an eight-person In the line of new results with

- cooperative from two departments at the classical designs I wish to report onUniversity of Southampton. Such fiber two developments. R. Wyatt and col-lasers--if end-pumped by, say, a diode leagues at the British Telecom Researchlaser and if provided with feedback mir- Labs described progress with grating-rors--allow for attaining a very low tuned external cavity semiconductoroscillation threshold and a very com- lasers. Their single-transverse-mode

pact, simple, cheap packaging. Weaker InGaAsP chip had one face (the output

2

"" " ~~~~~~~. . . . . . . . .. . . . . .... . .. ..".-"- "-'."" ' " "" "'' '' ' ". . . . . . . • - . ii

face) uncoated; the other facet was pete with stimulated Raman scattering.equipped with an antireflection coating, Under suitable conditions, the colli-and it illuminated a collimating lens. sionally pumped resonance level may beThe overall cavity was formed between inverted with respect to the lower levelthe diffraction grating (1200 lines/mm) of the Raman laser, and a stimulatedand the laser output facet. Tunability col-lisional induced laser is produced.over 100 nm around 1.5 pm was easily ob- In the second half of the talk, a some-tanned, with a 10-mW collimated output. what related discussion of weakly boundThe device, now available in a packaged exciplex lasers was given. Probablyversion, has very good spectral perform- these may be pumped by flashlight orance and should be useful for coherent other incoherent sources. Some experl-optical fiber communication detection, ments are in progress.sensors, and general spectroscopic and High-power Raman amplifiers werenonlinear optics applications, the topic of a sophisticated review

The second paper on improvements lecture by M. Shaw (Rutherford-Appletonwith standard systems that attracted Laboratory). The highlight of his reportmuch attention was presented by I.D. on new research was a discussion of hisCarr and described the work of a Physics work on three-wave mixing in molecularDepartment group at the University of hydrogen where a pump input from theSouthampton on injection seeding of a huge KrF laser Is combined in a light-Nd:Yag laser to give a high-quality, guiding Raman cell with the Stokes out-single-longitudinal-mode operation. A put, to give the highly amplified outputsingle frequency "mini-Yag" master os- (at the difference-frequency, ofcillator was pumped by a 20-mW GaAs course). He also made the point that inlaser, and, through a Faraday isolator, his view, KrF excimer lasers will turnits output was fed into a Q-switched out to be the "ultimate" means forslave laser (a telescopic Nd:Yag rod fusion experiments, since by pulse com-laser, giving l00-mJ output in a 30-ns pression and Raman amplification in con-pulse). The slave oscillator had a junction with optical multiplexing,tuning control (so far manual, but ideal tailoring for efficient operationeventually to be replaced by an automat- and target isolation can be achieved.ic piezoelectric mirror feedback control The third paper related to Ramancircuitry). Of course, the injected systems was given by D.J. Biswas anddominant mode forces a nearby single R.G. Harrison (Heriot-Watt University,mode to be excited very rapidly, thus Edinburgh), who reported the first ex-winning out over competition with other perimental verification of instabilitiesmodes (which would be also excited if leading to chaos in a single-mode homo-noise drove the oscillator). The ob- geneously broadened Raman laser system.served single-mode output burst had The route to chaos is characterized byexcellent quality characteristics. Cur- period doubling. The steadiness of therent work aims at stabilization and op- pulsations during uniform pumping sug-timization, so that single longitudinal gest single mode instabilities at rela-mode operation can be maintained indef.- tively low excitation above the thresh-initely. old. The laser used in the experiments

Raman lasers and related topics had NH3 as its active medium, was pumpedseem to have made a comeback. First of near-resonantly on the aR(6,0) transi-all, T. Duncan read a paper from Queen's tion by a CO2 laser, and emitted on an*1niversity, Belfast, which discussed aP(8,O) transition at 12.8 um. The talksome novel techniques suitable for the was delivered with the usual enthusiasmproduction of tunable, high-power ultra- of the Heriot-Watt Physics Departmentviolet (and possibly vacuum ultraviolet) group; but I fear that the speaker'slasers with a narrow bandwidth. The final statement--to the effect that dis-authors pointed out that stimulated col- covery of chaotic states in nonlineari1sional induced fluorescence can com- dynamics is as epoch making as was the

3

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discovery of quantum mechanics 70 years corresponding intensity of aboutago--must have turned off several people 100 W/cm2) was needed to achieve bista-in the audience. ble operation, with switching times as

low as a few milliseconds.Nonlinear Optics Apart from the Heriot-Watt scien-

I believe there were two coherent tists, another research cooperation (be-sets of talks on topics in nonlinear op- tween the RSRE and the Redhill Labora-tics that deserve reporting: (1) opti- tories of Philips Research) also had in-cal bistability, and (2) nonlinear phase teresting news to report. These col-conjugation. leagues investigated optical bistability

The first group of talks ties in in GaAs/AlGaAs multiple quantum wellnicely with the last paper I described structures. Both dispersive and absorp-in the previous section. Three big tive bistability has been observed. Thegroups from Heriot-Watt University re- former was achieved with 5-mW inputported on topics such as transverse power on the long wavelength side of aswitching waves and cross-talk of bista- Fabry-Perot resonance peak at 844 nm,ble elements, two-photon induced quasi- which is consistent with the increase ofcontinuous-wave optical bistability in the refractive index with temperatureInSb at room temperature, and thermally (as opposed to the electronic contribu-induced optical bistability in ZnSe thin tion to the nonlinear refraction). Ab-film interference filters. sorptive bistability, in turn, was ob-

To start with, the researchers served at wavelengths greater thanpointed out that the attainment of pro- 852 nm (of course, no Fabry-Perot cavityjected 1010_1012 b/s processing rates was needed in these experiments). Thefor parallel, all-optical switching ar- switching upon increase of the inputrays will depend strongly on the space- power is from high to low transmission--

bandwidth (spatial resolution) of the i.e., one now has a clockwise hysteresisarray. Thus, transverse coupling be- loop.tween switching elements must be mini- As I indicated above, a second pre-mized. The so-called "switching wave" ferred topic in the area of nonlinearphenomenon has been anlayzed and the re- optics was phase conjugation and degen-searchers found that, in case of a non- erate four-wave mixing. I want to de-linear Fabry-Perot etalon, the behavior scribe briefly three interesting papers.of switching waves is critical to the The first two came from Trinityresponse time, output intensity profile, College, Ireland, with W. Blau, C.the degree of hysteresis, and the cross- Maloney, W.M. Dennis, and D.J. Bradleytalk between adjacent devices, as authors. The researchers reminded

Other members of the group reported the audience that optical phase conjuga-on experimental progress. Apparently, tion in the near infrared should bequasi-continuous wave optical bistabil- given more attention than is customary,ity in the infrared has been observed in since optical fiber communication in theInSb at room temperature. It occurred 1.3- to 1.5-iim range offers importantaround the two cavity resonances which applications. They also pointed outwere obtained by nonlinear tuning of the that the use of organic dye solutionsetalon through two spectral ranges. A for picosecond degenerate four-wave mix-second team achieved optical bistability ing is a neglected topic, and it wasin the visible (500 to 700 nm) range in precisely this field that the research-thin film interference structures made ers explored. The best success wasfrom ZnSe. They think that a band gap achieved with a recently synthesizedresonant process, presently interpreted compound, designated S501*, which has an

as a thermal shift of the band edge, absorption maximum between 1.1 andresulting in a sensitive change of the 1.6 um. The experiments (performed withindex of refraction, is the responsible 100-ps pulses of a Nd:Yag laser) uti-mechanism. Input power below 10 mW (and lized a retroreflection geometry. With

4

all three incident light pulses polar- the pulsations may alternate between twoized in the same direction, large sig- distinct values. The transition to thenals could be observed. Phase conjugate "off" state is always accompanied by areflectivities of 100 percent were ob- very small frequency shift of the phasetained with an input pump pulse intens- conjugate beam.ity of 0.78 GW/cm at a sample transmis-sion of 0.5. The authors concluded that Quantum Opticsthe mixing process arises from thermally The majority of presentations ininduced refractive index changes in the this area focused around optical effectssolvent, which are not describable in terms of

In a related second paper, the fluctuating classical fields, but re-Trinity College physicists addressed the quire the formalism of the quantum theo-issue of searching for efficient non- ry of radiation. A splendid introductionlinear media for phase conjugation that to this field was given by L. Handelare cheap and easy to manufacture. They (University of Rochester, New York). Hesuggested that conjugated organic poly- pointed out that most nonclassical phe-mers seem very promising, since they nomena can be described as falling inhave a large delocalized ir-electron sys- one or another (or several) of the fol-tem which gives rise to high nonlinear lowing categories:polarizabilities. In their experimentsthey studied in detail optical phase 1. Photon antibunching (fewer pho-conjugation in solutions of polydiacety- tons arrive close together than furtherlenes in toluene and in chloronaphtha- apart).lene. These solutions have an absorption 2. Sub-Poissonian photon statis-maximum near 480 nm. One major conclu- tics (the fluctuations of the photonsion of the experiments was that the number are smaller than for a Poissondominating process is a thermally in- distribution).duced refractive index change in the 3. Correlated two-photon statessolvent. Furthermore, they believe that (photons appear in pairs rather thanthe response of the temporal coherence singly).of a particular component of the nonlin- 4. Squeezed states (one canonicalear susceptibility tensor is the conse- [quatrature] component of the electro-quence of a Kerr-like nonlinear inter- magnetic field fluctuates less than itaction process, would in tl,e vacuum state).

Since phase conjugation using thephotorefractive effect has become an In the rest of this session, Iarea of great interest, I will conclude found the talk by J.G. Walker and E.this section with a brief report on the Jakeman (RSRE) particularly stimulatingUniversity of Essex and ',itherford Ap- and simple. These authors suggestedpleton Laboratory coopciation (R.W. that light with sub-Poissonian and anti-Eason, A.C. Smout, M.C. Gower) that was bunched photon statistics could be con-the subject of a post-deadline paper. veniently generated by using a techniqueThese authors observed a novel self- in which a photoelectron-triggered opti-pulsing behavior in the well-known pho- cal shutter is used in conjunction withtoferroelectric material, barium titan- parametric down-conversion. They pro-ate. They noted that the intensity of ceeded to describe a possible experi-tht reflected phase conjugate beam mental arrangement. Coherent ultravio-,.iriez between the "on" and "off" states let laser light passes through a shutter.r, a regular fashion, without any appar- and impinges on a nonlinear uniaxial

ont externa' Influence. The self-pulsa- crystal (say, ADP). When the correcttion hji a period which depends on the phase matching conditions are satisfied,IncId,!nt laqei power. The exact charac- the incident photons "split" into pairster of the pulses is determined by the of lower frequency. Consider, then, two-,rvstl orientation. The amplitude of detectors placed at opposite ends of a

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.. . . . . .

diameter of the annular projection of cation of one of the components in thethe hollow cone on the detection plane. measured superposition is more than com-Each of these detectors will register a pensated by the effects of amplifierPoisson photon-arrival-rate distribu- noise. Thus, contrary to suggestions bytion. Since, however, the photons are skeptics regarding the standard inter-emitted in pairs, cross correlation of pretation of quantum interference, thethe output from the two detectors will insertion of an amplifier will onlyshow that the photon arrivals are coin- degrade to some extent the ability of ancident. Now use the output pulses from interferometer to provide "new" informa-one of the detectors as a trigger signal tion on the fundamental nature of light.to operate the shutter, which is so con- Two additional papers (Imperialstructed that it remains closed for some College and University of Essex) pro-preset time interval, after which It vided further studies on squeezed opti-opens. This process introduces not only cal states; but I will only report on"dead times" following counts in the one additional, remotely related paper,trigger channel but also into the repli- presented in the second oral session onca photon train incident on the second quantum optics. This was given by N.G.(monitor) detector. The counts in the Walker and J.E. Carroll (Cambridge Uni-trigger channel are obviously sub-Pois- versity). The work was concerned withsonian and antibunched. Yet the opti- the quantum theory of multiport opticalcal field between he shutter and the homodyning. At microwave frequenciesdetector is not free for use. This can the multiport technique for measuringbe seen by inserting a be,-m splitter phase and amplitude of a signal is nowinto this channel to divert a portion of well established and used in cou__ica-the light for analysis: one will find tion systems. The authors entertainedai optical field with bunched photon the hope that multiport techniques mayitatistics. The reason is that the di- be also applied in optical communica-verted photons are not involved in the tion--for example, to build a receivertriggering process, and the shutter acts for a multilevel phase shift keying sys-or'yv as a chopper as far as the photon tem, or for constructing a phase insen-neam is concerned. On the other hand, sitive detector for use in an amplitudethe replica beam ip free for use, and shift keying system. The authors devel-its properties can be monitored by the oped a rigorous quantum theoieticalsecond detector. The talk ended with a treatment of multiport homodyne detec-brie' report on the actual preliminary tion, and applied it to a dual balancedexperimental observation of antibunched receiver configuration which measureslight. the complex amplitude of one of the in-

A second, elegant and erudite talk puts to a 4x4 directional coupler. Byin this session, by R. Loudon and M. Ley exciting one of the unused input ports(Essex University), outlined the funda- into a squeezed ground state, they thenmental properties of optical amplifiers derived the homodyne equivalent of thein terms of the relation between their squeezed two-photon coherent state het-gain and the minimum amount of noise erodyne measurements which were de-that quantum mechanics requires the scribed in the literature a few yearsdcvie to add to the amplified signal. ago. Finally, the Cambridge scientistsThe inserting of such amplifiers into discussed measurements where only oneinterferometers produces effects that input port, other than the local oscil-can be easily analyzed by standard ele- lator, is excited.mentary quantum theory techniques. Thiswas done for both the Hanbury-Brown andTwiss experiment and also for the Mi- Even though no breakthroughs werechelson interferometer. The scientists reported, nor were unexpected or contro-showed that any improvement in interfer- versial results communicated at thisometer performance produced by amplifi- conference, I feel that it was a good

6

meeting and surved a very good cause. A Dual Wavelength Synchronously Mode-The regilar, tradition-based, organized Locked cw Dye Laser, T.F. Lillico,yet very free interaction of senior, i.S. Ruddock, and R. Illingworth,mid-career, and very young (pre-PhD) University of Stratclyde.scientists and experimental engine-rs is Raman and Collisional Induced Lasers,a great and laudable enerprise. I was D.G. Cunningham, H. Cormnican, I. Dun-told that this year's conference showed can, and T. Morrow, Queen's Universi-a novel feature: there was a greater ty, Belfast.proportion of workers from industry and A Flashlamp-pumped Dye Laser in a Tele-

applied government labs (relative to scopic Resonator Configuration, P.A.academics) than ii the previous years. Routledge, A.J. Berry, and T.A. King,Concomitant to this was an increased Manchester University.proportion of less fundamental and more Multi-Wavelength Operation of Rare-Gas-device-application-type contributions. Halide Lasers, R.C. Hollins and D.L.Perhaps this may give cause for concern, Jordon, RSRE, Malvern.but a good balance will be surely main- Tunable Semiconductor Lasers with Narrowtained by future organizing committees. Spectral Linewidth at 1.5 Vm, R.The next conference in now already being Wyatt, K. Cameron, and J. Devlin,prepared: it will take place in 1987 at British Telecom Research Laborator-St. Andrews in Scotland. ies.APPENDIX: CONFERENCE PAPERS Injection Seeding of a Nd:YAG Laser to

give Single Mode Longitudinal Opera-

. lasers tion, I.D. Carr, A.I. Ferguson, andRecent Advances in Spectroscopy with D.C. Hanna, University of Southamp-

Femtosecond Optical Pulses, C.V. ton.Shank, AT&T Bell Labs, US. Spectral Characteristics of Free-Running

Sub Pico.-econd Compression Optimisation and Injection-Locked HgBr Lasers,and Application of Optically Com- H.J. Baker, A.M. Feltham, and N. Sed-pressed Nd:YAG Laser Pulses, A.S.L. don, University of Hull.Gones, W. Sibbett, and J.R. Taylor, Single Mode Neodymium Fibre Lasers, R.Imperial College, London. Mears, D.N. Payne, S. Poole, L.

High Repetition Rate Operation of Copper Reekie, I.P. Alcock, A.I. Ferguson,and Gold Vapour Laser, A.J. Kears- D.C. Hanna, and A.C. Tropper, Univer-ley*. A.J. Andrews+, R.R. Lewis+, and sity of Southampton.C.E. Webb+, *Oxford Lasers, +Claren- High Efficiency Operation of RF Exciteddon Laboratory. CO2 Lasers, P. Vidaud, D. He, J.G.

Flashlamp-Pumped Lasing of Ch'omium: GSG Xin, P.J. Wilson, and D.R. Hall, HullGarnet, M.J.P. Payne and H.W. Evans, University.RSRF Malvern. Theoretical and Experimental Studies of

Demonstration of Self-Pulsing Instabili- Synchronously Pumped Dye Lasers, J.M.ties in a Single Mode Homogeneously Catherall, K. Smith, and G.H.C. New,Broadened Raman I 'ser, R.G. Harrison Imperial College.and D.J. Biswas, Heriot-Watt Univer- High Power Raman Amplifiers, M. Shaw,sity, Edinburgh. Rutherford Laboratories.

Passive Mode Locking of a cw Dye Laser A High Power Synchronously Pumped Dyein the Red/Near Infra-red Spectral Laser System, D.C. Hanna*, D.J.Region, K. Smith, N. Langford, W. Pointer*, and K.A. Ure+, *UniversitySibbett, and J.R. Taylor, Imperial of Southampton, +J.K. Lasers.College, London. Towards a Tunable Laser Glass, D.B. Hol-

Laser-induced Autoionisation in Xenon, lis*, S. Parke*, and M.J.P. Payne+,M.H.R. Hutchinson and K.M.M. Ness, *University of Sheffield, +RSREImperial College, London. Malvern.

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- .. . .. o-. . ........... ,..... . . .? .":- - -% '~~~~~..- . . . . . . . . . . . . . . . . . . . . . . ......-.-".i -" % -, -- ' ..-. .... "..--

2. Nonlinear Optics Acoustic Decay Time Measurements of SBS

Transverse Switching Waves and Crosstalk Hypersound in Heavy Gases at Elevated

of Bistable Elements, I. Galbraith, Pressures, M.J. Damzen, M.H.R. Hutch-W.J. Firth, D.J. Fagan, H.A. MdcKen- inson and W.A. Schroeder, Imperial

zie, J..J.E. Reid, A.C. Walker, J. College, London.

Young, and S.D. Smith, Heriot-Watt Degenerate Four-Wave Mixing of Picosec-University, Edinburgh. ond Light Pulses in Soluble Polydiac-

Two Photon-Induced Quasi-cw Optical Bi- etylenes, W.M. Dennis, W. Blau, andstability in InSb at Room Tempera- D.J. Bradley, Trinty College, Ire-tures, A.K. Kar, Wei Ji, U. Keller, land.J.G.H. Mathew, and A.C. Walker,Heriot-Watt University, Edinburgh. 39. uantum Optics

Thermally Induced Optical Bistability in Squeezed States and Non-Classical Sta-ZnSe Thin Film Interference Filters, tistics, L. Mandel, Rochester Univer-M.R. Taghizadeh, J.G.H. Mathew, I. sity.

Janossy, and S.D. Smith, Heriot-Watt The Description of Two-Mode SqueezedUniversity, Edinburgh. States of Light, S.M. Barnett and

Absorptive Optical Bistability in GaAs! P.L. Knight, Imperial College, Lon-AlGaAs Multiple Quantum Wells, A. don.

Miller*, G. Steward*, P. Blood+, K. Output Squeezing for Quantum OpticalWcodbridge+, *RSRE, Malvern, +Philips Systems: Quadrature Phase Spectra,

Research Laboratories, Redhili. M.J. Collett, University of Essex.Room Temperature Band Gap Resonant Opti- Theory of Interferometers with Optical

cal Nonlinearities in CdHgTe, D. Amplification, M. Ley and R. Loudon,Craig, A. Miller, and M.R. Dyball, Essex University.RSRE, Malvern. Generation of Antibunched Light Using a

Nonlinear Guided-Wave Optics, A.D. Triggered Optical Shutter in Paramet-Boardman*, P. Egan*, and G.I. Stege- ric Down Conversion, J.G. Walker andmen+, *University of Salford, +Uni- E. Jakeman, RSRE, Malvern.versity of Arizona. Nonclassical Effects in Light Emitted by

Compensation of Thermally-Induced Bire- Three-Level Atoms, A. A]-Hilfy and R.fringence in - Nd:YAG Amplifier Rod Loudon, Essex University.Using SBS Plase-Conjugation, I.D. Einstein's Rates and Rabi's Flops: ACarr and D.C. lanna, University of Quantum Optician's View of Resonance,Southampton. P.L. Knight, Imperial College,

Picosecond Nonlinear Optical Phase Con- London.

Jugation in the Near Infra-red, C. Detailed Analysis of Active Mode-LockingMaloney and W. Blau, Trinity College, Dynamics, L.A. Zenteno, H. Avramopou-

Ireland. los, and G.H.C. New, Imperial Col-

Experimental Study of the Dependence of lege, London.the Phase Conjugation Properties of Exact Analysis of the Effects of Black-Stimulated Brillouin Scattering (SBS) Body Radiation and of Finite Cavity Q"s a Function of Laser Coherence on the Fluorescence and AbsorptionLength, G.M. Davis* and M.C. Gower+, from one or more Rydberg Atoms in a*Clarendon Laboratories, +Rutherford Cavity, G.S Agarwal, R.K. Bullough,

Appleton Laboratories. and G.P. Hildred, UMIST.Measurements of the Nonlinear Suscepti- Interaction of Three-Level Atoms with

bility of Liquid Crystal Materials in Modulated Lasers, D.T. Pegg, Grif-the Isotropic Phase, A.M. Scott*, fiths University, Australia.

F.C. Saunders*, and P.A. Madden, Critical Behaviour and Quantum Optical*RSRE Malvern, +University of Ox- Bistability of the Tavis-Cummingsford. Model in a Driven Low-Q Cavity, R.K.

8

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* Bullough, S.S. Hassan, G.P. Hildred, Fringe Visibility in Optical Ramsey* and R.R. Puri, UMIST. Spectroscopy, B.J. Dalton*, T.D.

Quantum Theory of Multiport Optical Ho- Kieu*, and P.L. Knight+, *University

modyning, N.C. Walker and J.E. Car- of Queensland, Australia, +Imperialroll, Cambridge University. College, London.

* /.. lectr-optics Devicesi 4.Electro-otc eie 6. Miscellaneous Applications

The Detection of Infra-red Radiation, 6. iseaneos A lctosC.T.Ellitt, SRE.The Impact of Modern Electro-optics onC.T.the Industrial cene, G.W. Hamilton,

All-Optical Digital Circuits and Their Barr, and Stroud.

Application to Optical Computing, Laser-reflEXPFS and its Applications toA.C. Walker, J.C.H. Mathew, M.R. Surface Studies, R.W. Eason*, D.K.Jaghizadeh, F.A.P. Tooley, B.S. Wher- Bradley+, J.D. Hares+ A.J. Rankin+rett, S.D. Smith, and B.S Wherret, Brde+ J..HrsA'.Rni+

ret, SD. mit, ad BS Werrtand S.D. Tabatabaei+, *University of

Heriot Watt University, Edinburgh. and S Imperial *Unve

r[xcite-Probe and Three Pulse Studies of Essex, +Imperial College.:alnAsP, P.. Manning+, A. Miller+, Laser X-Ray Microscopy, R.W. Eason+,(a-iA . . "anlg+ Ma " ir P.C. Cheng*, R. Feder*, A. Michettet,and A.M. ko*, +RSRE Malvern, *Univ- R.J. RosserO, F. O'NeilO, Y. Owan-

danoQ, P. RumsbyO, M. ShawO, Essex

Spetroscopj_ University. *IBM, US, tKings College,(:ener, tion of int iise Narrowband 243 nm London, OSUNY, <>Rutherford Appleton

Radiation a in' its Application to Two Laboratories, UK.;'1otoel "oipier Free Spectroscopy of The AC Stark Shift for Pulsed Pumps,th, ilvdrmgcu IS-2S Transition, J.M. P.T. Greenland, AERE Harwell.

Barr, I.M. Barr, J.M. Girkin, J.M. Dynamic Picosecond Studies of OpticallyT,,-hLid, and A.1. Ferguson, South- Excited Silicon, I.W. BoydO, A.L.

ampton >- iversity. Stnirl*, T.F. Boggess*, S.C. Moss +,• it Sr iulated Raman Scattering in *North Texas State University, +Aero-

,,-, - d liquids, D.C. Hanna, D.J. space Corporation, US, OUniversity<.t.:r. >.IT.T. Pacheco, University College London.

iJpton. An Introduction to Molecular Electron-[c,r- r,-rietric Frequency Measurement of ics, J.O. Williams, UMIST.

"'jirsltions Near Balmer 6 in Optically Bistable Interference Fil-S ' -. /drogen and n-uterium, J.M. ters--Optimisatlon Considerations,

_ .M Barr*, .I Ferguson*. B.S. Wherrett, A.K. Kar, D. Russell,. . kr', ,1+, P. (;ii , R.C. D. Hutchings, and H. Clement, Heriot-

,.C. Thompson+, -S Th- Watt University.

"*tv, Nattonal Physical Degenerate Four-Wave Mixing in Flames,* S.V. O'Leary and P. Ewart, University

1 .,t of NOCQ-Stimulated of Oxford.

- ihrationaIIy Inverted Iaser Cooling of Magnesium Ions Confined

e ,h.,ra, I. (;illan, D. in a Penning Trap, R.C. Thompson,S.,-7-rw, a;id '.D. Mc(;arth, (,.P. Barwood, and P. Gill, National

-r-4tv le ,st. Physical Laboratory.

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