Single Mode Buried Polymer Waveguides on Silicon Substrate
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(SiO 2 ) (Single mode buried polymer waveguides) BPM CAD (trench) (Benezocy-clobutene, BCB) (guiding layer) SiO 2 (bottom cladding layer) (etching back method)bcb (top cladding layer) (cut back method) (propagation loss) (coupling loss) TE 0.91dB/cm TM 0.97dB/cm 0.06dB/cm 1.78dB?
Abstract In this paper, a single mode buried polymer waveguide on silicon dioxide layer on silicon substrate is presented. The waveguide was completed by first obtaining the optical field distribution using a beam propagation method. The waveguide structure is carefully designed to ensure a single-mode operation of this device. The waveguide was fabricated by first etching a trench on SiO 2 layer. Then Benezocy-clobutene (BCB) polymer was deposited onto the layer and cured in proper conditions. Finally, a thin hybrid sol-gel layer was used as the top cladding layer after the BCB polymer etch-back process. The propagation losses are 0.91dB/cm and 0.97dB/cm for TE and TM polarized lights. The polarization dependent loss is 0.06dB/cm. The coupling loss of the waveguide is 1.78dB.
1 6 2-1. 6 2-2. 9 2-3. 13 16 3-1. 16 3-2. 17 3-3. 27 30 4-1. 30 4-2. 30 4-3. 33 36
2-1 8 2-2 BCB 10 2-3 Sol-gel 13 2-4 14 3-1 17 3-2 SiO 2 20 3-3 BCB 22
1-1 5 2-1 2-2 BCB 8 11 2-3 BCB 12 2-4 15 3-1 16 3-2 BCB 21 3-3 Sol-gel 23 3-4 26 3-5 28 3-6 29 4-1 31 4-2 32 4-3 32
4-4 35 4-5 35
??? (Planar light wave circuit, PLC) (PLC) (optical switch)
PLC Dense Wavelength Division Multiplexing, DWDM?? (Flame Hydrolysis Deposition, FHD) [1] silica-on-silicon? FHD SiO 2 (polymer)? (polymer)[2,4,6]? (low propagation loss) (high temperature/thermal coefficient)?
? (coupler) (optical splitter) (filter) (optical switch)?? ( buried waveguides ) ( ridgewaveguides ) ( diffusion waveguide ) ( laser diode) ( optical detector )?? (micro-prism bending) [9] (branch) [10]?
PECVD SiO 2 cladding layer? SiO 2 (spin-coating)? (sol-gel)[11] Beam Propagation Method (BPM) CAD? BCB BCB sol-gel? (propagation loss) (coupling loss)?
? core core core?
?? BPM CAD? 2-1 2-1 PECVD 10µm SiO 2 (n SiO2 )=1.565? (dry etching) SiO 2 5µm 5µm (trench) (Benezocy-clobutene, BCB)[3]BCB (n BCB )=1.578? sol-gel 1µm (n sol-gel =1.47) (top-cladding layer)?
[9,12]?? PECVD? PECVD?
Sol-gel Thickness SiO 2 BCB Silicon n 2-1 layer index(for?=1.3µm) thickness(µm) top-cladding layer(sol-gel) 1.565 1 core layer (BCB) 1.578 5 bottom-cladding layer(sio 2 ) 1.47 5 2-1
2-2. BCB sol-gel? Cyclotene 4026-46 BCB 2-2? sample? BCB sample BCB? BCB sample? (prism coupler) [10,11]1.3µm BCB 1.3µm?
Property value Dielectric Constant(1kHz~20GHz) 2.65 Dissipation Factor(1kHz~1MHz) 0.0008 Volume Resistivity(O-cm) 1x10 19 Thermal Conductivity(W/m k) 0.29 T g () >350 CTE(ppm/) 52 Viscosity 1100 Stress(Mpa) 28 2-2 BCB 2-2 BCB 5000rpm 7.3µm? BCB Sample BCB etching back 5000rpm? 2-3 BCB 1.570~1.578 ; 200 BCB BCB BCB (glass transform temperature,t g )350 BCB Confinement factor?
Thickness(um) Speed(rpm) 2-2 BCB 1.579 1.578 1.577 1.576 1.57834 1.57826 1.57732 1.5776 TE TM Index 1.575 1.574 1.573 1.57464 1.57496 1.572 1.57122 1.571 1.57046 1.57 175 200 225 250 275 300 325 350 375 Curing temperature() 2-3 BCB
Si-1114 sol-gelsol-gel [11] inorganic organic sol-gel?? sol-gel?? sol-gel sol-gel 2-3 (rpm) (m) 1000 3.5 1250 2.1 3000 1.5 4000 1.2 5000 0.7 Sol-gel
5000rpm 0.7µm sol-gel 1µm 170 1.47 sol-gel? 2-3. [5,8,12]? BPM CAD? Confinement factor Spot size? 2-4 2-4
Spot size 4.8µm 4.2µm Confinement factor 89.2% Coupling loss to single mode fiber 1.2 db 2-4 2-4
2-4 BPM CAD Spot Size 4.8µm 4.2µm 89.2% 1.2 db??
[8,12]3-1 3-2 3-3? 3-1. Sample Sol-gel Cr BCB Etch back BCB Cr SiO 2 3-1
3-2. Sample Sample Acetone? Sample Isopropyl Alcohol? Sample DI water? Sample 120? () Cr (Thermal Evaporation ) 5.0 10-6 torr 75 Amp 0.4 Å /sec
3000 Å Photo-lighthography AZ4210 500rpm 10 5500rpm 40sec sample? ot plat 100 90sec I-line 45secAZ4000 30~40sec? 120 120sec Cr? Cr (wet etching) 120ml 100ml Cr-7T? sample Cr-7T 60sec 50Å/sec?
SiO 2 (Reactive Ion Etch, RIE ) sample RIE power (O 2 ) 80W 15 mtorr 6 s.c.c.m 10 min (Reactive Ion Etch, RIE ) (Electron Cyclotron Resonance, ECR)SiO 2
POWER (SF 6 ) RIE=100W; ECR=200W 8~10mtorr 6 s.c.c.m 83 min 602 A /min 3-2 SiO 2 Cr (1) sample Cr-7T Cr? BCB Sample BCB Sample 500rpm 60sec 5000rpm 40sec? BCB Sample 70 sample?
Temperature() Curing Time (min 3-2 BCB BCB etch back BCB etch back AZ4620 4000rpm 40sec Sample hot plat 120 120sec? BCB BCB
RIE=100W, ECR=200W 8~10 mtorr SF 6 =6 s.c.c.m ; O 2 =4 s.c.c.m 1967 Å/min 3-3 BCB sol-gel Sample 5000rpm 40sec sol-gel? sol-gel sample
Curing Time() Temperature(min) 3-3 Sol-gel? Cr Cr SiO 2 Silicon
PR Cr SiO 2 Silicon PR Cr SiO 2 Silicon n Cr SiO 2 Silicon n
SiO Cr SiO 2 Silicon SiO 2 Silicon BCB BCB SiO 2 Silicon
BCB PR BCB Cr SiO 2 Silicon BCB BCB SiO 2 Silicon Sol-gel BCB Sol-gel SiO 2 Silicon 3-4
3-3. Cr SiO 2 3500Å sample Cr Cr 3000 Å Cr? sample 50 ~60? SiO 2 sample 5 sample 3
sample? 3-5 SiO 2 SEM 5µm 5µm? 3-6 sol-gel BCB SiO 2 Silicon substrate? 3-5
3-6
?? 4-1 sample?sample sample UV Pyrex-7740 sample UV UV sample Pyrex-7740 UV? 4-2. Blue-tape
Pyrex-7740 UV-epoxy Sol-gel BCB SiO 2 Silicon substrate 4-1? 0.3µm Al 2 O 3 90sec 90sec Al 2 O 3 0.05µmAl 2 O 3 120sec 120sec Al 2 O 3? 4-2
4-3? 4-2 4-3
4-3 [11,12]? coupler( )input 632.8nm Hi-Ne Laser input 1.3µm laser diode?coupler output polarizer input TE TM? output detector detector HP 4155 detector HP 4155? (1) 1.3µm lader diode (propagation loss)? ( cut-back method)[10]? Pi Po db
? a = 10 Log P P o i ------- (1) α (db) P i P o 4-5 4-5 TE 0.92dB/cmTM 0.98dB/cm 0.06dB/cm 1.78dB?
Polarizer 1310nm 632.8nm Hi-Ne Len Couple Lens Lens Waveguide Lens Detector HP4155 4-4 Semiconductor Parameter analyzer Loss (db) TE:y = -0.9185x - 1.7839 TM:y = -0.9795x - 1.662 ength (cm) 4-5
? sol-gel sol-gel sol-gel? BPM CAD? TE 0.92dB/cmTM 0.98dB/cm 0.06dB/cm 1.78dB, TM : 1.66Db? sol-gel sol-gel?
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