集成光波导 完整版.ppt

Integrated Optic Waveguide,1 Dielectric Slab Waveguide,n,3,n,2,n,1,d,Trapping of light ray in a waveguide,n,2,n,3,q,2 MODES IN THE SYMMETRIC-SLAB WAVEGUIDE,n,2,n,2,n,1,n,1,n,2,Range of for bound waves:,Propagation factor,Longitudinal propagation factor,For an axial ray,=90 and n,eff,=n,1,For a critical angle ray =,c,and,The range of n,eff,is now,Define the,effective index of refraction:,2.1 Mode Condition,n,2,n,2,n,1,n,1,n,2,The two boundaries(upper and lower)form a cavity.A cavity is resonant when the round trip phase shift is 2m(where m=1,2,3).,=m2(10),2.2 TE and TM Polarization,TE polarization(Transverse Electric),This is the same as perpendicular polarization(s).,E,d,n,2,n,2,n,1,z,y,z,TM polarization(Transverse Magnetic),This is the same as parallel polarization(p).,(11),where we used the relationship,2.3 TE Mode Chart,Example,Consider an AlGaAs Laser Diode,For the TE,0,mode the calculations yield the table:,(1),(2),(3),(4),(5),(6),q,n,eff,tan(hd/2),hd,2,p,n,1,cos,q,d/,l,80.4,3.550,0,0,3.757,0,82,3.565,0.651,1.155,3.148,0.367,84,3.580,1.261,1.780,2.364,0.753,86,3.591,2.161,2.275,1.578,1.442,88,3.598,653,2.718,0.789,3.445,90,3.600,3.142,0,2.4 Higher Order Modes,(12),(13),q,n,eff,D,(d/,l,),(d/,l),2,80.4,3.550,0.836,0.836,1.672,82,3.565,0.998,1.365,2.363,84,3.580,1.329,2.082,3.410,86,3.591,1.991,3.433,5.424,88,3.598,3.980,7.425,11.40,90,3.600,(d/,l),0,0,0.367,0.753,1.442,3.445,(d/,l),1,TE,0,TE,1,TE,2,TE,3,TE,4,TE,5,d/,l,n,eff,q,Example:Let d=1.64 m,=0.82 m.,Find,n,eff,and the number of allowed modes.From,the mode chart(next slide):,TE Mode Chart,d/,l,n,eff,q,In general,the m-th mode cuts off(no longer propagates)when d/,l,satisfies:,(14),To insure only the TE,0,mode will propagate,make,This produces a single-mode waveguide.,(17),In a multimode waveguide:,Lower-ordered rays travel with larger angles than higher-ordered rays.,Lower,Higher,TE,0,TM,0,TE,1,TM,1,d/,l,q,n,eff,2.5 TM Mode Chart,Degenerate mode,Single mode propagation is obtained by,satisfying(17),and polarizing the light as TE or TM.,cos(hy),TE,0,TE,1,sin(hy),y,y,e,-,a(,y-d/2),e,-,a(,y-d/2),d/2,-d/2,2.6 Mode Pattern,cos(hy),TE,2,TE,3,sin(hy),y,y,d/2,-d/2,e,-,a,(y-d/2),3 Modes In The Asymmetric Waveguide,d,n,3,n,2,n,1,z,y,Example:Letn,1,=2.29 ZnS(zinc sulfide),n,2,=1.5 glass,n,3,=1.0 air,TE,0,TM,0,d/,l,n,eff,q,4 Coupling To The Waveguide,n,2,n,2,n,1,d,Light,source,1Edge Coupling,n,2,n,2,n,1,1,0,(21),Define the,fractional refractive index change,as:,Assume that,n,1,and n,2,are nearly equal.Then,Finally,Cladding Modes,Consider rays beyond the critical angle,(n,2,Axial mode,L,2,n,2,c,Higher order mode,L,1,5.2Multimode Distortion(Modal Distortion),Axial mode travel time:,For the critical angle ray,L,1,L,2,c,The total path of the critical angle ray is then,The total delay is,(27),The total pulse spread is given by,6 Integrated Optic Components,6.1 Passive Devices,Integrated Optic Directional Coupler,Substrate,L,P,1,P,2,P,3,P,4,For an ideal(lossless)coupler the relative output powers are given by:,P,2,/P,1,=cos,2,(,p,L/2L,c,),(30),P,3,/P,1,=sin,2,(,p,L/2L,c,),(31),where L,c,is called the,coupling length,.,Any splitting ratio between the two output ports is possible by appropriate choice of length L.,Example:If the actual length L of the coupling region is L,c,/2,compute the output coupling.,P,2,/P,1,=cos,2,(,p,/4)=(0.707),2,=0.5,P,3,/P,1,=sin,2,(,p,/4)=(0.707),2,=0.5,50%of the power exits both of the output ports.Since,10 log P,2,/P,1,=10 log 0.5=-3 dB,this is a 3-dB coupler.,integrated optic power splitters,P,in,/2,P,in,P,in,/2,6.2 Active Devices,Light Control Devices,Beam Switches,Modulations,Light Conversion Devices,Light Sources(Transmitters),Photodetectors(Receivers),The electrooptic switch,+V-,Applied E field due to V,Power In,off,on,As in the passive coupler,the power distribution is given by:,P,2,/P,1,=cos,2,(,p,L/2L,c,),P,3,/P,1,=sin,2,(,p,L/2L,c,),L is the interaction length and L,c,is the coupling length.,The interaction length L is set equal to the coupling length L,c,P,2,/P,1,=cos2(/2)=0,P,3,/P,1,=sin2(/2)=1,Mach-Zehnder Modulator,Input,Output,V,Optoelectronic integrated circuits(OEICs),combine optical and electronic functions on the same substrate.Fiber optic transmitters,receivers,and repeaters can be produced in this format.,6.3 Optoelectronic Integrated Optics,。