Optical Modulator Development at Partow …...Results For MZI Modulators • V π.L as low as 4 V-cm...

Optical Modulator Development at Partow Technologies LLC

CEO: Payam RabieiPartow Technologies LLC, Vista, CA

Company introduction

• Currently Partow is developing various optical modulators based on its bonded lithium niobate thin film technology.

• We have a phase II SBIR award from DOE and a phase I SBIR award from NASA.

• Our goal is to commercialize thin film based lithium niobatemodulators for data communication, analog photonics, and photonic sensing applications

• Relocated to California in 2016• Have access to state of art nanofabrication facility at UCSD

and UC Irvine

Propitiatory, for government review onlyPartow Technologies LLC

History

• The company started in Oct 2012 by Dr. Payam Rabiei and Prof. Sasan Fathpour at CREOL at University of Central Florida

• Received a first SBIR funding in 2014• Currently employs two full time staff as well as

contractors and part time staff

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Technical Summary

• Room Temperature wafer bonding• Lithium niobate thin film substrates• Optical modulator projects

Propitiatory, for government review onlyPartow Technologies LLC

Room Temperature wafer bonding

• Home designed and made high vacuum room temperature wafer bonding system

• Uses plasma surface activation and wafer press in high vacuum to bond dissimilar materials at room temperature

Propitiatory, for government review onlyPartow Technologies LLC

Very strong bond strength

-1

-0.5

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 2 4 6 8 10 12 14 16 18

Bond

stre

ngth

(J/m

2)

Activation Time (s)

Wafer Type A

Wafer Type B

Wafer Type C

Linear (Wafer Type A)

Linear (Wafer Type B)

Linear (Wafer Type B)Silicon surface energy

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Room Temperature wafer bonding

• Applications – Advanced photonic substrates– Advanced MEMS substrates– Wafer level vacuum packaging– Transparent bonding for various optical applications

• Features– Universal wafer to wafer bonding– No thermal stress (can bond dissimilar substrates)– No high force required ( i.e. can be used for bonding

fragile substrates such as III-V semiconductors)

Propitiatory, for government review onlyPartow Technologies LLC

Advanced substrates

i) Ion implantation

LiNbO3 Silicon

SiO2

ii) SiO2 deposition on Si substrate

iii) Wafer bondingiv) Heating

~2000 nm

~600 nm

LiNbO3

Silicon

SiO2

Silicon

SiO2

LiNbO3

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Thin film LN on Si substrates

X-cut LiNbO3 SiPartow Technologies LLC Propitiatory, for government review only

Advanced substrates

• Low loss optical quality thin films using in house bonding capability

• Possibility of bonding on a variety of different substrates.

• Almost universal and can be applied to create waveguide quality thin films on any flat substrate

Propitiatory, for government review onlyPartow Technologies LLC

Thick film substrates

• Used to achieve 5 microns and thicker LN layers by mechanical thinning methods

i) Wafer bonding ii) Thinning

~2000 nm

>6um

LiNbO3

Silicon

SiO2

Silicon

SiO2

Propitiatory, for government review onlyPartow Technologies LLC

Customers for wafer bonding

• Ultrasonic transducer manufacturers• X-ray detector manufacturers• Several federal research institutes in US• Several universities performing research in

MEMS, Optics, and a variety of other fields

Propitiatory, for government review onlyPartow Technologies LLC

Chalcogenide loaded LN device

Si

LiNbO3

SiO2

ChG

Si

LiNbO3

SiO2

Mask (SiO2)

ChG

i) ChG deposition ii) SiO2 mask e-beam lithography

Si

LiNbO3

SiO2

iii) ChG etching Passivation

ChGBCB

• Chalcogenide glass can achieve lower losses• Index is matched to lithium niobate

Partow Technologies LLC Propitiatory, for government review only

Ring resonators based on CHG on LN

• Q is as high as 1.3× 105

• Loss as low as 1.2 dB/cm

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Modulator electrode design LN

• Using high contrast waveguide electrodes can be placed closer

• -> Lower Vp

electrodes

Slab: LiNbO3

Ridge: Ta2O5

Cladding: SiO2

Si

SiO2

SiO2

y-cut LiNbO3E

z

y

VTa2O5

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Results For MZI Modulators

• Vπ.L as low as 4 V-cm is obtained

• Calculation shows Vπ.Las low as 2 V-cm is possible

-0.5 0 0.50

10

20

Pow

er (µ

W)

-0.5 0 0.5-10

0

10

Time (msec)

Vol

tage

(Vol

t)

Ta2O5

SiO2

LiNbO3Si

Au

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High speed testing setup

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High Speed MZI Characterization

• Modulator functioning up to several GHz

• The 8GHz drop in measurement due to detector

• Optical bandwidth >8GHz

• Some issues remain with non flat response to be addressed in phase II

2 4 6 8 10-16

-12

-8

-4

0

4

S 21 (d

B)

Modulation frequency (GHz)

Electrode transmission Optical response

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Grating coupling

• Low Loss couplers are needed to make a complete device

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Coupler measurement

• -6dB /coupler loss measured on LN samples with BCB cladding

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Low loss GC development

• Optimized grating coupler design achieved 3dB loss from the LN high index waveguide to single mode fiber

• An integrated micro-mirror for fiber couplingg

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DC drift problem

• Modulators with above design drift quickly over time• DC drift is eliminated by etching into the LN thin

films.

Propitiatory, for government review onlyPartow Technologies LLC