Microphotonics Readiness for Commercial CMOS Manufacturing. Marco Romagnoli

Size: px

Start display at page:

Download "Microphotonics Readiness for Commercial CMOS Manufacturing. Marco Romagnoli"

Evelyn Payne
5 years ago
Views:

1 Microphotonics Readiness for Commercial CMOS Manufacturing Marco Romagnoli MicroPhotonics Consortium meeting MIT, Cambridge October 15 th, 2012

2 Passive optical structures based on SOI technology Building blocks Waveguide Directional coupler Microring Polarization splitter and rotator Fiber coupling Laser butt coupling Component AWG Echelle grating Lattice filter 2

3 Waveguide SiO2 Si Si (substrate) Single mode waveguide (TE mode) Buried (Si core SiO 2 cladding) Core Size ~ 200 x 500 nm Lower Cladding (BOX) Height 3 mm 3

4 Waveguide Loss Substrate leakage 25,00 20,00 25,0 TE Pol TM Pol α prop [db/cm] 15,00 10,00 5,00 0,00 12,3 8,0 9,2 6,7 13,1 2,7 8,2 2,3 4,5 2,5 3,7 2,5 2,3 2, Waveguide Width [nm] Weak guidance Scattering loss 2,0 1,8 3,4 2,4 3,5 1,2 Waveguide thickness = 220 nm 4

5 Waveguide Loss Line edge roughness (LER) Method monitoring s and L c based on SEM image analysis. Demonstrated a correlation between roughness, statistical parameters and propagation losses in a straight waveguide Lot # s (nm) L c (nm)

6 Waveguide Loss coherence length L c (nm) α scattering [db/cm] WG height = 220nm WG width = 450nm (λ = 1.55 µm, Pol = TE) α [ db/cm ] W = 400nm W = 450nm W = 500nm L C = 40nm standard deviation σ (nm) σ [ nm ] Scattering losses increase with coherence length. Scattering losses decrease with waveguide width. 6

7 Waveguide Loss 1.7 ± 0.25 db/cm 12 SOI (2mm BOX), 65nm node at CNSE (University of Albany)

8 Waveguide Polarization Evolution STRAIGHT WAVEGUIDE TAPERED FIBER L = 6 mm TAPERED FIBER POLARIMETER W= 250nm 300nm 350nm 400nm 488nm TE TM 50 nm SCAN ( nm) waveguide thickness 220 nm 8

9 Directional Coupler For instance 2% error in coupling coefficient corresponds 2.6% in power splitting ratio. This error is mostly due to optical proximity effect. The error in gap-width is usually negligible. Proximity error 9

10 Microring Tolerances Parameter Effective index sensitivity /nm GHz/nm /nm GHz/nm Tunability c - 70 GHz/nm 10 GHz/ C W thickness W width Intrachip statistics on resonance fluctuation: = 27 GHz (0.22 nm) R Gap 12 SOI (2mm BOX), 65nm node at CNSE (University of Albany) W ring 10

11 Microring thermal tuning, trimming and power consumption M. R. Watts et al, CLEO/QELS

Microring athermal coupler 0.1 0.095 0.09 T = 25 C T = 125 C T = 225 C K Cross [normalized] 0.085 0.08 0.075 0.07 7.9%±0.4% 8.3% 7.9% 7.5% 0.065 0.06 0.

12 Microring athermal coupler T = 25 C T = 125 C T = 225 C K Cross [normalized] %±0.4% 8.3% 7.9% 7.5% λ (nm) Athermal directional coupler Decrease of coupling coefficient with temperature is compensated for by increase of mode size at the new resonant wavelength. This feature implies that changes of filter shape are negligible in the 4 THz tuning range nm nm nm Tx [db] Thru T0 Drop T0 Thru Tmax Drop Tmax , , , , , ,250 Freq [THz] 12

13 Microring Tuning & Trimming 4 THz filter thermal tuning b) contact contact microheaters microheaters r ing First channel Last channel 13

-25-30 Residual TM Residual TM -35-40 1.5 1.

14 Polarization Handling Polarization splitter & rotator 0-5 TM TE -10 Power (db) Residual TM Residual TM Wavelength (mm) Spurious TE 14

15 Polarization Handling Polarization splitter & rotator performance Straight Si waveguide Polarization diversity scheme 0 SWG 0 PsP_T - 12 ASE_TE1nm TM ASE_TM1nm OVA_TE OVA_TM ASE_TE0,01nm Tx [db] TE ASE_TE1nm ASE_TM1nm OVA_TE OVA_TM ASE_TE0,01nm ASE_TM0,01nm Tx [db] ASE_TM0,01nm Wavelength[nm] Wavelength [nm] 15

16 Fiber coupling Side view SM fiber 80 mm 2 modal area SiO 2 SMF SiO 2 :(Ge) 1 µm 220 nm Si waveguide Buried Oxide Si substrate Top view Input Taper Si Wg 0.1 mm 2 modal area (500 X 220 nm) Vertical Coupling SMF SiO 2 :(Ge) Tip 110 nm Silicon waveguide 500 nm 16

17 Fiber coupling Tolerances to mask misalignements and sensitivity to Si tip loss 2 25,00 Vertical coupling loss (db) α prop [db/cm] 20,00 15,00 10,00 5,00 0,00 25,0 12,3 8,0 9,2 6,7 13,1 2,7 8,2 2,3 4,5 2,5 3,7 2,5 2,0 2,3 2,5 1,8 TE Pol TM Pol Waveguide Width [nm] 3,4 2,4 3,5 1,2 10 db/cm Si tip loss 5 db/cm Si tip loss Mask misalignement (mm) TE/TM average loss 17

18 Grating coupler Fiber coupling Single polarization Dual polarization IEEE J. of Sel. Top. in Quant. El., 17, p. 597 (2011) 18

19 III-V DFB Laser Butt Coupling Air gap Gain Chip On submount Straight SOI waveguide w=1.4um Tapered Lensed fiber Spot size 1.7 um Working distance 4 um Butt-coupling alignment and no taper: InP/SOI best coupling loss = -4.2 db (experimental) (theoretical best case = -3.5 db) Extra 3 db loss with less than 1µm lateral offset and/or 3µm air gap Butt-coupling alignment with InP spot size converter (SSC) and taper on SOI: InP/SOI best coupling loss = -0.5 db (theoretical) Extra 1 db loss including less than 1um offset and/or 4µm air gap 19

20 AWG Laser Photonics Rev. 6, No. 1, (2012) 20

21 Echelle Grating Laser Photonics Rev. 6, No. 1, (2012) 21

22 Lattice Filters 22

23 thank you!

Silicon Photonics: A Platform for Integration, Wafer Level Assembly and Packaging

Silicon Photonics: A Platform for Integration, Wafer Level Assembly and Packaging M. Asghari Kotura Inc April 27 Contents: Who is Kotura Choice of waveguide technology Challenges and merits of Si photonics