11:45am-I2:00pm Th15 rl 1 kierrnally i,imablc polarissiiin convertcr Cor

WUM liltering w,pplimi,ions Ton i<osi,er and Pad Larn1)cclc

M RSA+ rcscarcli iiistitiit.c, 1'0 Sox 217, 7WO AP: Enschcdc, T h o Ncthcrlnrids I'lioiir +31-63-4892719, Fax +:11-53-489394:1, email 1.iri.koslcr(alal,utwcntc.iil

1. ~NTILODIJCTION

Gratiiig ;tssist,c!d co iqk r s can I)(! nsed i is wavelengl,lr selecl.ive coinponeiit,s in WDM tlcvic:es. IIere, we present, for the first. timc n t,lierrrially t,nricd polarisation convert,cr, wiih wtiidi i i rclilt,ivc tuning range of 2% of tlic ccnt,rc wavelength ciin he achieved for il 50K increasc of the ternp,c!ratmc: of the heater electrodc.

2. I'OLARISKI'ION CONVERTlX~

A i c "3

A _______.. ........... A' B ........... ......

F l c r l R E 1 . a)Strnctuie of the converter, 1b)Typical wavelength responst!.

In figure la, the polarisation converter, realised in SiON-pnlymer technology, is shown. It, is i i

co-direct,ional grating assisted coupler consisting of alternat,ing sections of asymmetrical (et,ched) ridge wavegnide segments. Duc t,o this asynimct,ry, at, each transit,iori between adjacent. segments, the polarisation angle of the light is slightly rotated. The polarisation rotatioii is wavelengt,h dependent, the wavclengt,h for optimum conversion being given by A, = - N , l . M ) h , with NTR and N T M t,hc cffcctive indicxs of t,hc lowcst ortlcr TE and T M mode, rcspcctivcly, and A tho grat,ing period. In figlire lb) itn cxperirriciit,;illy ol)t,aiiiccl cnrvc of (,lie conversion vorsiis wavelcngt,h is shown.

3. THERMAL TUNINC

The centre wavelength of the convcrt,or is a function of NT, - N ~ , M , which in its turn is a function of thc Iayycr thicknesses and itidices of the optical layer system. As the refractive indices of the optical layers arc temperatiwe dcpciirtmit, iind t h e optical Iicld distribution of the T E and T M niode differ, this caritre wavclcngt,h citii bc t,un(xI by hcatirig the optical latyw sysle~ri using ;i

heater elec1,rorle. The shift, in t,hc wiwctlcngt,li is iipproxima1,ely given l)y

(3.1)

With T the heater t,eniperat,ure ancl TO t,hc ambient, (background) t,enipcr;~i;iirc.

0-7803-5947-Xf00/$10.0002000 IEEE 7 64

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