Microphotonics Readiness for Commercial CMOS Manufacturing

Microphotonics Readiness for Commercial CMOS Manufacturing

Marco Romagnoli

MicroPhotonics Consortium meeting MIT, Cambridge

October 15th , 2012

© 2011 Scuola Superiore Sant’Anna

Building blocks •  Waveguide •  Directional coupler •  Microring •  Polarization splitter and rotator •  Fiber coupling •  Laser butt coupling Component •  AWG •  Echelle grating •  Lattice filter

2

Passive optical structures based on SOI technology


Waveguide

•  Single mode waveguide (TE mode)

•  Buried (Si core – SiO2 cladding)

•  Core Size ~ 200 x 500 nm

•  Lower Cladding (BOX) Height 3 mm

Si

SiO2

Si (substrate)

3


1,23,5

13,112,3

9,2 8,2

4,53,7

2,3 2,53,4

25,0

2,41,82,02,52,52,32,7

6,78,0

0,00

5,00

10,00

15,00

20,00

25,00

150 200 250 300 350 400 450 500 550 600 650 700 750Waveguide Width [nm]

α p

rop [d

B/c

m]

TE Pol TM Pol

Substrate leakage

Scattering loss

Weak guidance Waveguide thickness = 220 nm

Waveguide Loss

4


Method monitoring s and Lc based on SEM image analysis. Demonstrated a correlation between roughness, statistical parameters and propagation losses in a straight waveguide

Line edge roughness (LER)

Waveguide Loss

5

Lot # s (nm) Lc (nm)

358 2.2 20

427 1.67 18

432 1.34 15

489 1.22 12


2.22

789

2.22789

2.22789

4.45578

4.45578

6.68368

6.68368

8.91157

8.91157

11.1395

11.1395

13.3674

13.3674

15.5

952

15.5952

17.8231

17.8231

20.0

51

20.051

22.2

789

22.2789

24.5

068

24.5068

26.7347

28.9626

31.190533.4184

35.646337.8742

40.102142.3299

44.5578standard deviation σ (nm)

cohe

renc

e le

ngth

L c (nm

)

α scattering [dB/cm] (λ = 1.55 µm, Pol = TE)

1 2 3 4 5 60

20

40

60

80

100

120

140

160

Scattering losses increase with coherence length.

WG height = 220nm WG width = 450nm

0.5 1 1.5 2 2.50

2

4

6

8

σ [ nm ]α

[ d

B/c

m ]

W = 400nmW = 450nmW = 500nm

LC = 40nm

Scattering losses decrease with waveguide width.

Waveguide Loss

6


12” SOI (2mm BOX), 65nm node at CNSE (University of Albany)

Waveguide Loss

1.7 ± 0.25 dB/cm


TAPERED FIBER

STRAIGHT WAVEGUIDE

POLARIMETER

L = 6 mm

TE

W= 250nm 300nm 350nm 400nm 488nm

•  50 nm SCAN (1520-1570nm) •  waveguide thickness 220 nm

TAPERED FIBER

TM

Waveguide Polarization Evolution

8


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


Microring Tolerances

0.0037 /nm

Tunability

- 270 GHz/nm

c - 70 GHz/nm

10 GHz/°C

0.0017 /nm - 130 GHz/nm

Parameter Effective index sensitivity

10

Wwidth

Gap

Wthickness

Wring

R Intrachip statistics on resonance fluctuation: = 27 GHz (0.22 nm) 12” SOI (2mm BOX), 65nm node at CNSE (University of Albany)


Microring thermal tuning, trimming and power consumption

11

M. R. Watts et al, CLEO/QELS 2009

2009


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.

1525 1530 1535 1540 1545 1550 1555 1560 15650.055

0.06

0.065

0.07

0.075

0.08

0.085

0.09

0.095

0.1

λ (nm)

K Cr

oss

[nor

mal

ized

]

T = 25°C T = 125°C T = 225°C

7.9%±0.4%

15

50

.0

nm

15

57

.7

nm

15

42

.3

nm

7.9%

7.5%

8.3%

-55

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

193,750 193,850 193,950 194,050 194,150 194,250Freq [THz]

Tx [d

B]Thru T0

Drop T0

Thru Tmax

Drop Tmax

Microring athermal coupler

12


4 THz filter thermal tuning contact

r ing

microheaters b)

contact

r ing

microheaters b)

contact

r ing

microheaters contact

r ing

microheaters b)

contact

r ing

microheaters contact

r ing

microheaters

Microring Tuning & Trimming

First channel

Last channel

13


Polarization Handling

1.5 1.52 1.54 1.56 1.58 1.6-40

-35

-30

-25

-20

-15

-10

-5

0

Wavelength (mm)

Pow

er (d

B)

TM TE

Residual TM

Residual TM

Spurious TE

Polarization splitter & rotator

14


SWG

-30

-25

-20

-15

-10

-5

0

1520 1525 1530 1535 1540 1545 1550 1555 1560 1565 1570Wavelength [nm]

Tx [d

B]

ASE_TE 1nmASE_TM 1nmOVA_TEOVA_TMASE_TE 0,01nmASE_TM 0,01nm

PsP_T - 12

-30

-25

-20

-15

-10

-5

0

1520 1525 1530 1535 1540 1545 1550 1555 1560 1565 1570Wavelength [nm]

Tx [d

B]

ASE_TE 1nmASE_TM 1nmOVA_TEOVA_TMASE_TE 0,01nmASE_TM 0,01nm

TM

TE

Polarization Handling

Straight Si waveguide Polarization diversity scheme

Polarization splitter & rotator performance

15


Input Taper Vertical Coupling

Tip 110 nm

500 nm Silicon waveguide SiO2:(Ge) SMF

Top view

SMF

1 µm

Buried Oxide

Si substrate

220 nm Si waveguide

SiO2:(Ge)

Side view SM fiber ≈ 80 mm2 modal area

Si Wg ≈ 0.1 mm2 modal area (500 X 220 nm)

Fiber coupling

16

SiO2


0 0.2 0.4 0.6 0.8

1 1.2 1.4 1.6 1.8

2

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

10 dB/cm Si tip loss

5 dB/cm

Si tip loss Verti

cal c

oupl

ing

loss

(dB

)

Mask misalignement (mm)

Tolerances to mask misalignements and sensitivity to Si tip loss

TE/TM average loss

Fiber coupling

17

1,23,5

13,112,3

9,2 8,2

4,53,7

2,3 2,53,4

25,0

2,41,82,02,52,52,32,7

6,78,0

0,00

5,00

10,00

15,00

20,00

25,00

150 200 250 300 350 400 450 500 550 600 650 700 750Waveguide Width [nm]

α p

rop [d

B/c

m]

TE Pol TM Pol


Fiber coupling

Grating coupler

Single polarization Dual polarization

IEEE J. of Sel. Top. in Quant. El., 17, p. 597 (2011)

18


Tapered Lensed fiber Spot size 1.7 um Working distance 4 um

Straight SOI waveguide w=1.4um

Gain Chip On submount

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

III-V DFB Laser Butt Coupling

19

Air gap


AWG

Laser Photonics Rev. 6, No. 1, 14–23 (2012)

20


Echelle Grating

Laser Photonics Rev. 6, No. 1, 14–23 (2012)

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Lattice Filters

22


email: [email protected]

thank you!

Microphotonics Readiness for Commercial CMOS Manufacturing

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