Shengrong Chen

Perfluorocyclobutyl Copolymers for Microphotonics

The copolymerization of aryl bis- and tris-trifluorovinyl other monomers aromatic perfluorocyclobutyl (PFCB) polymers, via thermally initiated stepgrowth cycloaddition chemistry. PFCB polymers and their copolymers enjoya unique combination of attributes well suited for applications in photonic technologies, such as broad tailorability of refractive indices and thermo-optic coefficients, low transmission losses as 1300 and 1550 nm, high thermal, mechanical, and optical stability, and excellent melt and solution processability. Planar PFCB structures lif can be processed by direct micro-transfer molding, which is a first step towards rapid soft-lithographic fabrication of polymer planar lightwave circuits. Copolymerization chemistry and processing parameters and characterization, including thermal (T g ≃120-350°C) and optical properties trefractive indices from 1.443 to 1.308 at 1550 nm, thermooptic coefficients dn/dT-7×10 - 5 K - 1 to -1.5×10 - 6 K - 1 ), birefringence (< 0.003), and temporal stability of refractive index, are described.

Arrayed waveguide gratings based on perfluorocyclobutane polymers for CWDM applications

Compact wavelength-division multiplexers based on arrayed waveguide grating structures have been designed and fabricated for short-haul communication network applications using low-loss perfluorocyclobutane-containing polymers. The devices exhibit high thermal stability and low on-chip losses. The average on-chip loss was <6 dB, including the fiber-to-chip coupling loss. The output uniformity across five channels was typically /spl plusmn/0.5 dB, and the thermal sensitivity of the central wavelength was 0.045nm//spl deg/C. Optimization of devices through material properties and fabrication process parameters is discussed.

Long-range surface plasmon polariton waveguides embedded in fluorinated polymer

Low-attenuation waveguides based on the propagation of long-range surface plasmon polaritons (LRSPPs) along thin Au stripes embedded in low absorption perfluorocyclobutane (PFCB) polymer are presented. A new low in propagation loss of <2.0 dB/cm was achieved for a 4 microm wide waveguide by optimizing the cladding material and fabrication process. The coupling efficiency between the LRSPP waveguide and the optical fiber is studied theoretically and experimentally for different widths of Au stripes and various cladding thicknesses. Lower coupling loss is found when the cladding thickness is close to the mode diameter of the butt-coupled fiber. Based on the 2D distribution of SPP modes calculated by a finite-difference mode solver, a symmetric structure of multilayer claddings with different refractive indices is proposed to optimize device insertion loss.

Novel perfluorocyclobutyl(PFCB) polymers containing isophorone-derived chromophore for electro-optic [EO] applications

Perfluorocyclobutyl (PFCB) polymers and copolymers have a unique combination of properties well suited for optical applications such as high temperature stability, precisely controlled refractive index, low moisture absorption, excellent melt and solution processability, a variable thermo-optic coefficient, and low transmission loss at 1300 and 1550 nm. Electro-optical devices from polymers of ring locked polyene chromophores are attractive due to their thermal, mechanical, optical and dielectric properties. Polyene chromophores with highest hyperpolarizability are covalently attached to trifluorovinyl aryl ether containing moieties and copolymerized with other monomers. The resulting polymers display imrpoved thermal stability, solubility and good film forming capabilities.

Property-tailorable PFCB-containing polymers for wavelength division devices

This paper demonstrates the application of property-tailorable perfluorocyclobutyl (PFCB) polymers to the fabrication of arrayed-waveguide grating (AWG) devices for use in wavelength division multiplexing (WDM) optical networks. This novel series of PFCB polymers exhibits low optical attenuation, high thermal stability, and tailorable refractive index, facilitating the design of high-performance photonic devices. The design, fabrication, and characterization of AWGs are reported in this paper. The fabricated devices show high thermal stability and low on-chip losses. Optimization of devices through the tailoring of material properties and fabrication process parameters is discussed. The successful fabrication of AWG highlights the potential of this material for other devices in photonic applications

Direct micro-transfer molding of perfluorocyclobutyl (PFCB) polymer waveguides

Perfluorocyclobutyl (PFCB) polymers and copolymers enjoy a unique combination of properties well suited for optical applications such as high temperature stability, precisely controlled refractive index, low moisture absorption, excellent melt and solution processability, a variable thermoptic coefficient, and low transmission loss at 1300 and 1550 nm. Copolymerization reactions offer tailored thermal and optical properties by simple choice of comonomer. PFCB copolymers can be solution or melt microfabricated via standard methods and can also be processed via micro-transfer molding in photolithographically generated features. Reliable molding of polymer waveguides offers significant potential to reduce photonic integrated circuit (PIC) fabrication costs and enable the realization of compact, integrated subsystems for a variety of applications. Copolymerization chemistry, thermoptic measurements, and initial results on the first micro-transfer molded waveguide structures are presented.

Property tailored perfluorocyclobutyl (PFCB) copolymers for optical devices

Organic polymers are increasingly attractive alternatives to inorganic materials in telecommunication devices. Polymers offer flexibility, low cost fabrication and connection, high transparency in the visible and near-infrared spectra, and versatility in structure, properties, and grades for task specific integration such as local-area-network applications. Halogenated polymers in particular show negligible transmission losses in the range desired and fluoropolymers represent the lowest loss examples of organic polymers to date. However, commercial perfluoropolymers in general are limited by poor processability, non-trivial refractive index matching, and they typically do not exhibit the thermal and thermomechanical stability required for some commercial processes and extreme environment in-use applications. Our strategy has focused on the thermal cyclopolymerization of trifunctional and bifunctional aryl trifluorovinyl ether monomers to perfluorocyclobutane (PFCB) copolymers. PFCB polymers and copolymers enjoy a unique combination of properties well suited for optical applications such as high temperature stability, precisely controlled refractive index, low moisture absorption, excellent melt and solution processability, a high thermooptic coefficient, and low transmission loss at 1300 and 1550 nm. Copolymerization reactions offer tailored thermal and optical properties by simple choice of comonomer. PFCB polymers can be solution or melt microfabricated via standard methods and can also be processed by soft-lithography techniques. Polymerization and processing parameters and characterization including thermal properties (Tg = 120-350 degree(s)C), optical loss (< 0.2 db/cm at 1550 nm), refractive index tunability (1.449-1.508 at 1550 nm), low birefringence, and optical stability is presented.

All-optical switching in microring-loaded Mach-Zehnder interferometer fabricated from perfluorocyclobutyl (PFCB)

We demonstrate that all-optical switching in a microring-loaded Mach-Zhender interferometer fabricated from PFCB is possible, and obtained a response pulse width of about 30ps and a maximum modulation depth of 3.8 dB.