Optical Modulator Development at Partow …...Results For MZI Modulators • V π.L as low as 4 V-cm is obtained • Calculation shows V π.L as low as 2 V-cm is possible-0.5 0 0.5

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

Partow Technologies LLC Propitiatory, for government review only

Technical Summary

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


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


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


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)


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


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


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


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


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


Ring resonators based on CHG on LN

• Q is as high as 1.3× 105

• Loss as low as 1.2 dB/cm


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


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


High speed testing setup


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


Grating coupling

• Low Loss couplers are needed to make a complete device


Coupler measurement

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


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


DC drift problem

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

films.


Documents

Optical Modulator Development at Partow …...Results For MZI Modulators • V π.L as low as 4 V-cm is obtained • Calculation shows V π.L as low as 2 V-cm is possible-0.5 0 0.5