Integrated Polymer Waveguides Research Articles

Automated Misalignment Compensating Interconnects Based on Self-Written Waveguides

Optical interconnects are the key components for integrated optics to link photonic integrated circuits or to connect external elements such as light sources and detectors. However, misalignment of the optical elements contained and its compensation is a remaining challenge for integrated optical devices. We present a novel method to establish rigid interconnects based on a 2-wavelength self-written waveguide process which automatically compensates for misalignment. We exemplarily demonstrate the capability of our process by writing interconnects between two multimode fibers as well as hot-embossed integrated polymer waveguides and a bare laser diode chip. The coupling efficiency of the interconnects obtained is analyzed with respect to misalignment. We found that coupling losses are as low as 1.3dB if a lateral misalignment lies within a 10 μ m interval, which is achieved by commercially available pick-and-place machines. Our approach is easily combined with high-throughput techniques such as hot embossing and enables low-cost production of interconnects even for mass fabrication in future applications.

Low-Cost Interfacing of Fibers to Nanophotonic Waveguides: Design for Fabrication and Assembly Tolerances

The high cost and low scalability of interfacing standard optical fibers to nanophotonic waveguides hinder the deployment of silicon photonics. We propose a mechanically compliant low-cost interface with integrated polymer waveguides. Our concept promises better mechanical reliability than a direct fiber-to-chip coupling and a dramatically larger bandwidth than diffractive couplers. Our computations show a 0.1-dB penalty over a 200-nm bandwidth, whereas typical two-polarization vertical couplers show a ~1-dB penalty over a 30-nm bandwidth. In this paper, we present a comprehensive analysis of the design space using optimization routines to achieve a fabrication- and assembly-tolerant design. We demonstrate the concept feasibility through extensive tolerance analysis with parameter control assumptions derived from low-cost manufacturing.

Evanescent-Field Excitation of Fluophores in Cultured Neural Networks by Integrated Polymer Waveguides

Monitoring the interface between adherent cells and their respective substrate using fluorescent methods traditionally depends on complex systems not suitable for all types of cell studies. We present a method for cell-substrate monitoring by optical waveguides fabricated using deep UV (DUV) modification of polymethyl methacrylate. This simple process allows neuronal cells to be grown directly on optical waveguides in a more conventional, <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in vitro</i> environment, similar to cells grown in Petri dishes. By using the evanescent field generated at the interface between the waveguides and cells, fluorescent molecules present in the cells can be excited within several hundred nanometers of the optical waveguides. Details on the DUV chemistry and fabrication technologies will be briefly outlined as well as proof-of-concept of fluorescent excitation using the evanescent field generated by optical waveguides.

Microfabricated polymer chip with integrated U-bend waveguides for evanescent field absorption based detection

A mu-TAS system for evanescent field absorption with integrated polymer waveguides is reported for the first time. A photoresist SU-8 layer is patterned into a microchannel network, with U-bend waveguides and fiber-to-waveguide coupler structures. The aim of this study was to explore the possibility of using evanescent field absorption based sensing in conjunction with capillary electrophoresis for label free detection. We have proposed a novel design to couple the microchannel network with U-bend waveguides in a single step patterning of SU-8. In this novel design, the optical waveguide forms part of the microchannel wall, which aids in the detection process. The suitability of the device for optical applications was proved by absorbance measurement between 450 and 780 nm using Methylene Blue dye. Absorbance measurements were done by passing various concentrations of dye solutions through 200 microm and 500 microm microchannels. The device was also found sensitive to the refractive index (RI) of fluid flowing in the channel. The RI sensitivity was tested by passing sucrose solutions of varying concentrations through the channels and measuring absorbance across the integrated U-bend waveguides. The results indicate that such structures can be used easily for label free detection of molecules either by evanescent wave absorption or by changes associated with RI changes in the microenvironment around a waveguide.

Laser‐assisted fabrication of monomode polymer waveguides and their optical characterization

AbstractThe local surface modification as well as the direct micro‐ablation of polymethylmethacrylate (PMMA) with UV‐laser radiation was studied with respect to the fabrication of optical monomode waveguides. Different UV sources were applied with a focus on excimer lasers and frequency‐multiplied Nd:YAG lasers to investigate several concepts of integrated waveguides. One type of waveguides is realized by localized physical modification, which leads in one step to an integrated polymer waveguide with higher refractive index. A complementary type of waveguides includes the formation of small grooves, which are filled with index matched materials introducing a micro‐scaled increase or decrease of the refractive index into the original PMMA substrate. The different laser‐assisted fabrication techniques for polymer waveguide formation as well as the characterization of their local optical properties are discussed in detail.

3-Gb/s data transmission with GaAs VCSELs over PCB integrated polymer waveguides

GaAs quantum-well (QW)-based vertical-cavity surface-emitting lasers (VCSELs) at 855-nm emission wavelength are investigated for intraboard polymer waveguide links. We report a 3-Gb/s pseudorandom bit sequence (PRES) nonreturn-to-zero (NRZ) data transmission over about 5-cm long printed circuit board (PCB) integrated multinode polymer waveguide arrays of two different geometries at bit-error rates (BERs) of less than 10/sup -11/.

Short-wavelength vertical-cavity surface-emitting laser applications: from high-throughput multimode fiber links to two-dimensional interchip interconnections

An overview is given of recent experiments employing 850 or 980 nm emission wavelength vertical-cavity surface-emitting laser diodes (VCSELs) for high-throughput very short reach optical data transmission. For future high-speed building backbones, we demonstrate the first transport of 40 Gbit/s data rates over 300 m of a new generation multimode fiber by means of a four-channel coarse wavelength-division multiplexing system. As an attractive route to overcoming high-speed electrical signaling problems on printed circuit boards, we show 10 Gbit/s per channel data transmission for densely spaced integrated polymer waveguides. Error-free VCSEL operation at 2.5 Gbit/s with a temperature range from -20 to +100°C indicates compatibility with most industrial requirements. Finally, we demonstrate 850-nm bottom-emitting VCSEL arrays for direct flip-chip bonding, which might prove useful for twodimensional future silicon chip-to-chip interconnect solutions.

Optical backplanes with integrated polymer waveguides

Optical backplanes with integrated polymer waveguides

Passive alignment of single-mode fibers to integrated polymer waveguide structures utilizing a single-mask process

A fabrication process for high precision passive fiber chip coupling is presented. The difficulties of structuring highly nonplanar surfaces were solved by using an electrophoretic photoresist and introducing additional structures to prevent wide holes. The method involves only a single lithographic step for structuring the polymer waveguide and fiber aligning structures in Si and thereby minimizing the horizontal displacement. The loss due to fiber displacement is about 0.7 dB per front face.