Observation of optical turbulence in a single mode homogeneously broadened optically pumped molecular laser

Observation of optical turbulence in a single mode homogeneously broadened optically pumped molecular laser

~ollllllc 54. lluIIIll~!: ? Instabilities leading 10 chaos in the emission from laser systems have receivedconsidcrablc attention since the first p...

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54.

lluIIIll~!: ?

Instabilities leading 10 chaos in the emission from laser systems have receivedconsidcrablc attention since the first prediction of such behaviour by I lakcu for a hornogcneously broadened system [I].

Rcccnt-

ly we here able IO demonsrrute chaotic pulsations in the 100 ns emission from a truly homogeneously broadened laser system; VL! a mid-infrared ( 12.8 pm and 12.08 ~ni wavelength) NH, laser optically pumppulsed CO2 laser radiation 12J. In IIICpresent paper we extend our results to essentially steady state

et1

by

conditions and use a short laser cavity length to cnsure sin@ ;utial ~nodcoperalion. To our krrowlcdgc this represenls the firsr dcrrmsiration of chaos in a single mode homogeneously broadened laser sysrcm. Wc iio1c hcrc the iwent dmonstration of period doubling by Weiss cl al. 13 ] in an extrerncly low prcssure system \iir an oprically pumped fdr infrared Cl I, l:2 laser. Routes to chaos via period doubling and also; inlermilicncy are clearly idernificd in our s]slcm. The gcncrarion of instabilities was

li~~nd IO

critically

dcpcnd on cavity length. NH3 was sclccred here OII l,hc basis of ils well docunienlcd discrete spectroscopic lixture, highly efficient mid-infrared king emission and ills0 our carlicr demonstration of instabilir its in this gas under passive (non-lasing) condilion (4 I. ‘I’cmporally smooth TC’Mt,,-, pump pulses wcrc dcrixxl iiottt a hybrid CO2 laser [S 1, the I’EA SW ion of which was a I .urrronics K-021 IIW~UIC. L.ong puks

(FWHM -2 /AS) 4 peak power 250 kW wcrc &t;lined by operating the low pressulc section above t hrcshold and using a N,-rich gas mixture in the TEA secrion 161 (see fig. I). The (10, laser operating on the FIR16 lint (1076 cm l ) pu~npcd the aR(6. 0) NH, lransition I .3 GI Ix below the lint centre. The Fabry-Perot St I, laser cavity. slightly offset to eliminate feedback to the CO2 laser cavity, was 24 cm long giving a frccspectral range of 624 MHz and consisicd of a gold CCXICRYC (2 111radius of curvature) mirror provided with piczoelectric runing (P7.T) I’acility and 21plane Gf! mirror (705 rcllcctiviity ilf 12.8 clnl and 8.5%.at 9 pm: for achcrnaticdetails see fig. 1). The NH, cmissiim occurred at 12.8 pm (aI’@. 0) transition) and lhc pulse duralion was approximately 2 PS compared to lhc cavity round lrip iimc (It<) of I.6 ns. For cxpcrimcnls on a dispcrsivc cavity. used lo tlccouplc the rotliati<)n aiicr a single l)ilss rhrough tllc NH’,

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et ill. [Is) 1 fi)r a resonantly exciled fiir infrared fwo tt!\cl s>SlClTl. acknowledge the SI:RC for partial

We graldutty

support of Ihis progrmmc. D.J.B. wishes to thank Rhahha .Alomic Rcsci\rdl Centrc for grating him lcavc oi’i~bscncc. I4c thank W.J. I%h. J. Maloney illld I. AI-Saidi iiN IlClplill discussions.

.I. (.BXllll. SyC57rov IL(llill I lillblr’: I .: I IHI !!I] (.‘. IWlirntl. II 6 (,;!;Glr- :III~ I IMI. \;!;)I. I’h>3. I cl:. 10 (IYXZ) 655 Op:ic\ ( QI:;III 5! 1iOh PI ( .() Heis> :Incl U Klww. 47 LlOl N.B. .Qrrli;r~u. I. (‘II! h. 11. (‘olcm:u~. K.S. (;iogd;b. S.J. Ili~hs, I..Y. Ildr’cr, S.Y. lb. M. 5iadn imtl .I.(‘. Wcsson. in: I.ecturc Xotcs in Plwicc. Vol. I82 (Spririgc’i Vcrlag. 1983) p. 105. fI.!:I!. I’ll). III, y. I’OIIlC:IU illlil I’. Villlll~~IIIc’. ~‘Oll:ll’llll. ‘4 I I 08(J) I HO I -I ” V.L. SIIIII. I’.\! Viloriiii :iIld 1.K. I~kc’rlbill:. :o Iv ITi I .U.

l;l>ll~l.

(1983)

pul~lirlietl.

References

I I .‘?I 1..,\.

LIl~!liil~~. I.. M. Xard:JCL’l. I) C. l1illXl> .Illtl ( 2

Pcnnhe. Opriir

II. Il;lkcn.

PII)\.

It (I. Ili~rr~w~ tlYh;l

l.c~r. 5.iA flY75)

and I.A. Al-Saidi.

77. Optics ~‘onm.

14

II!?

I{.(;

Ilxrwn.

I.Cll

53 IlYH4I

U.J. I iah and I.:\. II-Sdidi. I%)>. Kc\. 2.58; I< (I Ilillrl*~!fl. \..I. I irth. (‘. I.mblIiJr~ iIIld I:\. :\I-Silltll. l’ll)~. I<\?. I.~‘11 51 IlYti3) 562 \. ( ;t~rItlI:illtvkill. S.K. Ilskcnbclg iId I . IIoI/II~II~cI. I’ll!\

I Cll. -lo:1 I IYY.“rb 229.

5 I< Ilcckcnlxr;, ;wl!li~llcrl

t to

A.K.

Kw ml

.I.(; II. Va~lwa.

(‘omc:. 46 [I OX.\I h-l Ilodpes. I .R. I’OOI~ and I< I). ILvl. \;)pi. I%y, I i:rl. 29 (IV761 662. 1151 11.1). Uoi:iron. I3.K (Arwle ilnd I I~cIcI. II I I .I Oui~nt. I’lwrion 2(! I I YH4! I M!i I If-1 K.1. Ihock and I7 J. Iankill. II I’I J QIL~III I Icc:on 141 I’). I

IO Ix

II_

S I. Ilentlua antI Il. Siirpwl

Ill.

Op:ics ( ~II~II*: 4!!

I 108’1_ .ik5. I..\\ (‘ii,pCr\,o~l. II’! I J. ()lJillll. I ir!::-on 14 l,lY’?j tih 256 I IO C.O.H&c, \h. Klnd~. P.S. I rlrl!’ iIll \I (‘~H~;wI. ()I’liL*u (‘ornm. 52 I lYHS)Ji)S.