Technical Papers
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Recent Advances in Commercial Electro-Optic Polymer
Modulator |
Authors: Bing Li, Raluca Dinu, Dan Jin, Diyun Huang, Baoquan Chen, Anna Barklund, Eric Miller, Merly Moolayil, Guomin Yu, Yun Fang, Lixin Zheng, Hui Chen, Jeevan Vemagiri Abstract: We present the state-of-art polymer-based electro-optic modulator, which, for the
first time, can be used in real commercial systems. The devices work up to 100Gbps and
possess the Vπ as low as 1.6V.
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Novel hybrid electro-optic modulators with horizontal taper structure |
Authors: Guomin Yu, Bing Li, Danliang Jin, Lixin Zheng, Raluca Dinu and Antao Chen Abstract: Hybrid sol-gel/polymer electro-optic modulators with horizontal taper structure have been designed and
fabricated. Optical transition between sol-gel passive waveguides and electro-optic polymer waveguides via horizontal
tapers has been realized in the electro-optic modulators. With 1cm interaction length these hybrid electro-optic
modulators have been measured to have a half-wave voltage of 8.91 V (dual drive 4.45 V), an extinction ration of
21.2dB and an optical insertion loss of 11.8 dB.
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Optical Signal Processor
using Electro-Optic Polymer Waveguides |
Authors: Byoung-Joon Seo, Seongku Kim, Harold Fetterman, Dan Jin and Raluca Dinu Abstract: We have investigated an optical signal processor using electro-optic polymer waveguides at 1.55 μm. As a
result of recent polymer development many new optical devices are becoming available such as optical filters,
modulators, switches, multiplexers, etc. It would be useful to have a single optical device, which is reconfigurable,
to implement all of these optical devices functions. We call such a device an ‘Optical Signal Processor’, which will
play a similar role as digital signal processors in electrical circuits. We have realized such an optical device using
optical-delay-line circuits. Since optical-delay-line circuits are based on the multiple interference of coherent light
and can be integrated with enough complexity, they have been utilized for purposes of optical processing such
as optical filters. However, the guiding waveguides that were used are passive and the only mechanism used
to reconfigure their functions has been thermal. This is slow and cannot be used for high speed applications
such as optical modulators and optical packet switches. On the other hand, electro-optic polymers have a very
high electro-optic coefficient with a good velocity match between the electrical and optical signals which makes
them ideal for efficient, high speed, devices. Therefore, we have investigated delay line optical signal processor
circuits using the electro-optic polymer waveguides. These structures are complex enough to generate arbitrary
functions and fast enough to obtain high data rates. Using these optical signal processors, we have investigated
interesting applications including arbitrary waveform generators.
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Low half-wave voltage modulators using nonlinear optical polymers |
Authors: Danliang Jin, Diyun Huang, Baoquan Chen, Hui Chen, Lixin Zheng, Anna Barklund, Guomin Yu, Eric Miller, Merly Moolayil, Bing Li, and Raluca Dinu Abstract: The optical and material properties of AJ309 electro-optic (EO) polymer were systematically studied with the objective
to fabricate an optimized integrated device. Both bottom and top cladding materials were developed at Lumera to
match the processibility of AJ309, and sustain high poling voltage needed for an effective poling process. A device
fabrication process is developed. The degree of crosslinking of the EO polymer before poling is minimized by
processing the top clad polymer at room-temperature. The UV-curable top clad has shown no detectable chemical
damage to the EO polymer after the deposition process of the top clad, thus maintaining the integrity of the interface
between top clad and AJ309 core. A 2.1 cm long active length Mach-Zehnder modulator with low half-wave voltage
(Vπ) of 1.1 V @1550 nm was fabricated using the AJ309 EO polymer and in-house cladding materials. Other device
parameters are also reported.
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Electro-Optic Polymer Modulators as Passive mm Wave Detectors |
Authors: M. R. Fetterman, J. A. Grata, R. Dinu, M. Koenig , A. D. Visnansky, W. L. Kiser, Jr. Abstract: We have developed a first generation of electro-optic polymer modulators, designed specifically for passive millimeterwave
detection. The advantages of utilizing electro-optic polymers for modulator fabrication are their economical and
simple fabrication, potential for large scale array fabrication, and well matched RF and optical indices, which provide
the potential for an excellent high-frequency response. The current drawbacks of these devices include long term device
stability due to oxidation and the relative immaturity of the RF designs for the modulator and interconnects, which lead
to unacceptable internal losses and low sensitivity. These are both items we expect remedied in the upcoming year. We
provide a brief overview on the opto-electronic method of detecting millimeter waves and our design and fabrication of
the polymer modulator. Current measured results for the modulator response at 95GHz are presented and an analysis of
the required performance for imaging is presented.
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Hybrid Integrated Cascaded 2-bit Electrooptic Digital
Optical Switches (DOSs) |
Authors: Wei Yuan, Seongku Kim, Harold R. Fetterman, Fellow, IEEE, William H. Steier, Life Fellow, IEEE, Danliang Jin, and Raluca Dinu Abstract: Hybrid integrated cascaded 1 x 4 electrooptic (EO)
polymeric digital optical switches (DOSs) are proposed and demonstrated.
The hybrid integration of passive polymer on the same chip
withEOpolymer can lower the overall device loss without affecting
the EO effects. The cascaded DOS can be controlled by only two
voltage signal sources without bias stabling mechanism. The device
can be operated as a 2-bit reconfigurable switch. The switching
voltage is around 15 V for single arm driving with reasonable
extinction ratio (912 dB) and the loss is improvedby2.5 dB. This
device is ideal for implementing variable optical delay network.
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Comparison of r33 values for AJ404 films prepared
with parallel plate and corona poling |
Authors: Edward M. McKenna, Andy S. Lin, Alan R. Mickelson, Raluca Dinu, and Dan Jin Abstract: We report on the measured electro-optic coefficients of approximately 150 pm/V at 1310 nm and 1550 nm for
poled guest–host polymer films made with the chromophore AJ404L. Films were poled using corona poling and
parallel-plate poling techniques. The films were fabricated and poled and the electro-optic coefficients measured
by two independent laboratories. Corona-poled AJ404L films were spun onto indium-tin oxide-coated
glass substrates with and without a cladding layer of UV15LV. The r33 value for the films were measured using
the Teng–Man technique for both corona-poled and parallel-plate poled films.
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Development of polymeric electro-optic materials for
practical device fabrication |
Authors: Diyun Huang, Danliang Jin, Lixin Zheng, Don Tolstedt, Stephen Condon, Baoquan Chen, Dani Ianakiev, Eric Johnson, Amanda Cort, Anna Barklund, Timothy Parker, Raluca Dinu Abstract: Polymeric electro-optical modulators have the advantages in bandwidth, driving voltage, and cost over lithium niobate
modulator for potential industrial, military and space applications. There are strict requirements on electro-optical
polymer materials to be used for practical device fabrication: large EO response, high thermal and photochemical
stability, low optical loss, high long-term stability and good processibility. Lots of progress in material design,
modification and optimization has been made based on theoretical calculation and actual material processing. However it
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Packaged high-speed electro-optic polymer modulators |
Authors: Raluca Dinu, Danliang Jin, Diyun Huang, Mary K. Koenig, Anna M. Barklund, Yun Fang, Timothy C. Parker Abstract: Electro-optic (EO) polymer modulators have demonstrated high speed external modulation of optical signals.
Additionally, EO polymers have closely matched refractive indices at optical and microwave wavelengths, which
enables high bandwidth operation. An EO polymer includes a polymer matrix and an organic “push-pull” chromophore
that can be modified to give poled polymers with high EO activity. This high EO activity and optical-microwave
velocity match offer the promise of accomplishing broadband, high speed optical modulation with low drive voltage.
Such optical signal modulation is critical for applications in phased array radar and RF photonics. Practical issues such
as electrode design, optical fiber coupling, and hermetic packaging are critical in final device performance. Herein, we
report on high-speed electrode parameters as well as electro-optic performance versus frequency of packaged modulators
fabricated with novel, highly photostable chromophores.
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Development of New Host Polymers for Electro-Optic Modulators |
Authors: Lixin Zheng, Dan Jin, Dani Ialakiev, Eric Johnson, Diyun Huang, Don Tolstedt, Steve Condon, Anna Barklund, Amanda Cort, Baoquan Chen, Tim Parker and Raluca Dinu Abstract: Host polymers play an important role in determining the thermal, optical and electrical properties of guest-host electrooptic
(EO) polymers. In this study, a series of novel polymers, polyaryletherketones (PEKs) and polyarylethersulfones
(PES’), were synthesized. After an initial screening on EO modulator fabrication-related properties, a PEK, LP120, was
identified as a good candidate to host the highly stable chromophores (DH6 and DH52) developed in the company.
Further optimization indicated that solvents in chromophore/polymer solutions have a strong impact on the quality of
spin-coated films. DH6/LP120 and DH52/LP120 films spun from cyclopentanone gave lower optical losses of 1.97 and
1.55 dB/cm, respectively, when compared with 2.84 dB/cm for DH6/APC and 1.96 dB/cm for DH52/APC. Moreover,
poling efficiencies as being reflected by EO coefficient were also improved by using LP120 compared to APC.
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Low-driving voltage polymer modulators
with applications in space missions |
Authors: Raluca Dinu, Yun Fang, Mary K. Koenig, Anna M. Barklund, Danliang Jin, Diyun Huang, Bing Li, Timothy C. Parker Abstract: Low Vπ modulators are desirable in RF photonic and phased array radar applications. In general, there is still a need for
optical modulators that have lower drive voltage, lower loss, and large bandwidth to decrease complexity, expense, and
size in other parts of the packaged transmission system. This is particularly important for space based applications
where reducing launch weight is crucial. Polymer modulators potentially enable space-based RF photonics because low
Vπ can be achieved by modifying the organic constituents of the material. Additionally, polymers tend to have relatively
low loss tangent and good RF-optical velocity match, which enables broadband devices. One fundamental issue for
polymer modulator usability in space is the resistance of the materials to radiation. Previous reports have shown a small
but measurable change in modulator properties on irradiation with gamma-rays and protons. Herein we report on the
fabrication of polymer modulators, the results of irradiation, and potential lifetimes in earth orbits.
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Low-Voltage Electro-optic Polymer Modulators |
Authors: Raluca Dinu, Danliang Jin, Diyun Huang, Mary K. Koenig, Anna M. Barklund, Yun Fang, Timothy C. Parker, Zhengwei Shi, Jingdong Luo, and Alex K-Y. Jen Abstract: Electro-optic (EO) polymer modulators have demonstrated high speed external modulation of optical signals.
Additionally, EO polymers have closely matched refractive indices at optical and microwave wavelengths, which
enables high bandwidth operation. An EO polymer includes a polymer matrix and an organic “push-pull” chromophore
that can be modified to give poled polymers with high EO activity. This high EO activity and optical-microwave
velocity match offer the promise of accomplishing broadband, high speed optical modulation with low drive voltage.
Such optical signal modulation is critical for applications in phased array radar and RF photonics. However, practical
fabrication of optical modulators that realize the potential of EO polymers requires clad materials with optimized
properties such as conductivity, dielectric constant, optical loss, and refractive index. In addition, other practical issues
such as electrode design, optical fiber coupling, and hermetic packaging are critical in final device performance. We
report on high-speed electrode parameters as well as electro-optic performance versus frequency of modulators
fabricated on 6” silicon wafers. The r33 values measured on single layer thin films are compared with those resulting
from Vπ measurements on devices. We compare the effect of EO polymer morphology on device fabrication and optical
loss for different EO polymers.
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Wavelength dependence of irreversible photobleaching
of dye-doped polymer waveguide materials |
Authors: Ed McKenna, Jiuzhi Xue, Regis Fan, Lou Bintz, Raluca Dinu, and Alan Mickelson Abstract: We report the irreversible bleaching characteristics of 4-(dicyanomethylene)-2-methyl-6-(p-dimethyl
aminostyryl)-4H-pyran (DCM) doped into perfluorocyclobutene (PFCB) and a new material known as
DH-6 doped into amorphous polycarbonate (APC) by a monochromatic bleaching source. The wavelength
dependent rate constants for the irreversible bleaching process are found, and the experimental bleaching
characteristics are compared to the theoretical bleaching characteristics determined from a kinetic model
of the bleaching process.
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Metal-Defined Polymeric Variable Optical Attenuator |
Authors: SeongKu Kim, Yu-Chueh Hung, Kevin Geary, Wei Yuan, H. R. Fetterman, Dan Jin, Raluca Dinu, and W. H. Steier Abstract: A variable optical attenuator (VOA) based on a metaldefined
polymeric optical waveguide has been demonstrated for the
first time. The metal film stressor deposited on top of the upper
cladding layer not only produces the refractive index change within
the core layer, but also acts as a thin-film heater allowing thermal
tuning of the optical power within a metal-defined optical waveguide.
Fabricated devices exhibit greater than 25 dB of optical attenuation
with an applied electrical current of 40mAat 1550-nm
wavelength. The switching speed of the VOA exhibits 800 s of
rising and 720 s of falling time.
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Effect of Nano-architectural Control on Optical Loss in Electro-optic Polymers |
Authors: Diyun Huang and Tim Parker Abstract: Nonlinear optical chromophores have been used to
obtain guest-host and side-chain polymers. The polymers
are fabricated with crosslinking groups attached to both the
chromophores and the polymer backbones. The guest-host
composites often have micro domains that increase optical
loss of the material. When the chromophore is covalently
linked to the backbone, the micro domains are avoided and
the optical loss of the material is decreased by a factor of 2-
3 dB/cm. This nano architectural control is crucial to
produce polymer electro-optic devices that are
commercially viable.
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Low index electro-optic sol-gel materials |
Authors: Danliang Jin, Diyun Huang, Stephen Condon, HannWen Guan, Shuxin Cong, Anna Barklund, and Raluca Dinu Abstract: Polymeric electro-optic materials have made significant progress in increasing electro-optic co-efficient, enhancing
temporal stability, and lower optical loss at operating wavelength. To fully realize the electro-optic activity in a
waveguide device, appropriate cladding materials need to be designed carefully and a compatible fabrication process
should be developed accordingly, which has been challenging and tedious. It would be desirable if glass-based optical
fiber or silica substrate can be utilized as parts of device materials. The challenge is to match the relatively lower
refractive index of fiber and silica substrates. Thus, a low refractive (~1.44) of electro-optic material was designed. The
efforts include the synthesis and characterization of the low index host materials via sol-gel process and silanization of a
chromophore with large hyperpolarizability. In this study, an electro-optic sol-gel material with a refractive index
~1.44 at the wavelength of 1.55 μm was developed. It was highly processible and compatible with glass-based fiber or
silica-based materials. An interdigitated electrode configuration is designed and a substrate with such a configuration
was fabricated. Combined with the in-situ SHG monitoring setup, poling process can be readily monitored and
optimized. The r33 obtained at the wavelength of 1.3 μm is 19 pm/V. Thus, it becomes possible to design optical
devices using glass-based fiber or silica substrate as part of the device structure, which could simplify the material and
process development.
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Systematic Study of Electro-optic Materials Composed of Non-linear
Optical Chromophores and Polycarbonates |
Authors: Diyun Huang, Danliang Jin, Don Tolstedt, Stephen Condon, Dani Ianakiev, Hann Wen Guan, Shuxin Cong, Eric Johnson, Akiko Nishimoto, Raluca Dinu Abstract: Polymeric electro-optic materials have many potential advantages over their inorganic counterparts in both industrial
and military applications for the reason of bandwidth, driving voltage, and cost. To fulfill the device processing and
performance requirements, electro-optic materials need to possess high electro-optic activity, low optical loss, adequate
thermal and photochemical stability as well as long term alignment stability. In this work, first we have designed and
synthesized a series of chromophores with various acceptors. Their thermal stability and electro-optic activity were
compared. Detailed chromophore loading studies were carried out. An electro-optic coefficient of 160 pm/V was
achieved. Secondly we modified our chromophore bridge by adapting 3,4-ethylenedioythiophene moiety. Both thermal
stability and electro-optic activity are improved. Finally, we synthesized two polycarbonates with higher glass transition
temperatures and lower optical loss. Their guest-host systems show improved EO activity, optical loss and long term
alignment stability.
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Systematic Study of Polymer Wideband Optical Modulators:
Transition from Intrinsic Material Characteristics
to Device Performance |
Authors: Raluca Dinu, Timothy C. Parker, Diyun Huang, Dan L. Jin, Mary Koenig Abstract: Low drive voltage Mach-Zehnder modulators were designed and fabricated using proprietary EO polymers with high
electro-optic coefficients. We report on drive voltage and high-speed electrode parameters of modulators fabricated on
silicon wafers with high yield. Special attention was paid to designing claddings to match the electro-optic core
conductivity and dielectric constant. The r33 values measured on single layer thin films are compared with those
resulting from drive voltage measurements on devices. Half-wave voltage measured on devices is compared with
theoretical values derived from equations defined for poling of the core through bottom and top claddings. We compare
results obtained from devices fabricated using commercially available UV-curable epoxies with devices fabricating
using proprietary clad polymers developed at Lumera Corporation.
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Development of Side-Chain NLO Polymer Materials with High
Electro-Optic Activity and Long-Term Stability |
Authors:Diyun Huang, Timothy Parker, Hann Wen Guan, Shuxin Cong, Danliang Jin, Raluca Dinu, Abstract: The electro-optic coefficient and long-term dipole alignment stability are two major factors in the development of high
performance NLO materials for the application of high-speed EO devices. We have developed a high performance nonlinear
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Polymer blend LEDs using polyfluorene copolymers and
thermally cross-linked fluoropolymers |
Authors: Vincenzo Casasanta, Timothy Londergan, and Raluca Dinu Abstract: The use of conjugated light emitting polymers (LEPs) blended in non-conjugated matrices offers an enhancement in
electroluminescence efficiency in polymer light emitting diodes (PLEDs) since the aggregate quenching of the excited
state emission is ameliorated. In such a scheme the matrix polymer may be developed in order to enhance the thermal,
mechanical, and processing properties of the LEP blend as a whole. We have produced solution processable blends of
polyfluorene (PF) based copolymers with thermally crosslinkable perfluoroarylether (PFAE) polymers and tested these
materials’ performance as a single emissive layer in the simplest PLED structure. Specifically we present results of
blends consisting of red poly[{9,9-dihexyl-2,7-bis(1-cyanovinylene)fluorenyl-ene}-alt-co-{2,5-bis(N,N’-
diphenylamino)-1,4-phenylene}] as the LEP and a novel PFAE which is thermally crosslinked as the matrix. The new
PFAE has been specifically developed for low optical loss, high glass transition temperature (Tg), and solution processability.
Once spun cast and thermally crosslinked, films of these polymer blends show increased solvent resistance and
enhanced Tg due to the fluoropolymer matrix. Simple ITO/polymer/Al PLEDs of several concentration ratios are
fabricated and tested in order to determine the efficacy of various matrix additions. The light-current density-voltage
characteristics show either equivalent or enhanced efficiency depending on LEP/PFAE concentration. Blends of the
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Achieving Large Electro-Optic Response: DH-Type Chromophores In
Both Crosslinked Systems And Linear High Tg Systems. |
Authors: Dan Jin, Tim Londergan, Diyun Huang, Nick Wolf, Stephen Condon, Don Tolstedt, Hann Wen Guan, Shuxin Cong, Eric Johnson, Raluca Dinu. Abstract: Drawing on the success of the DH6-polycarbonate system, new derivatives based on the DH bridge structure, bis-1,2-
(dibutoxythiophene)vinylene have been synthesized and tested. The property-structure function has been investigated,
showing that location of the trifluorovinylether (TFVE) crosslinker on the chromophore has an impact on electro-optic
(EO) activity as well as stability. A crosslinked polymer, IMOH_PCT-R and a linear high glass transition (Tg) analog,
IMOH_HT, in combination with various DH derivatives are discussed. The temporal stability data of these systems
show comparable results for both crosslinked and linear polymers, furthering the argument that the Tg of the EO material
is the critical parameter in determining device lifetime.
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Material development and processing for
electro-optic device systems |
Authors: Danliang Jin, Raluca Dinu, Timothy C. Parker, Anna Barklund, Lou Bintz, Baoquan Chen, Christoph Flaherty, Hann Wen Guan, Diyun Huang, Jeffrey Kressbach, Timothy Londergan, Thomas D. Mino, Galina Todorova, Simon Yang Abstract: New crosslinked clad polymers were developed for electro-optic polymer modulators with special attention paid to
properties such as refractive index tunability, optical loss, and conductivity. These cured polymers showed relatively
low optical loss at 1550 nm and desirable conductivity. The clads were used to fabricate electro-optic devices having
mode profiles closely matched to that of optical fibers in order to reduce insertion loss. A new hardmasking technique
was developed to define Mach-Zehnder rib waveguides by photolithography and dry etching with high reliability and
surface smoothness. The hardmasking technique demonstrated flexibility in defining waveguides made with electrooptic
polymers having different reactivity towards etchant gasses.
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