Novel configurations and approaches for polymer electro-optic devices (original) (raw)
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Design and fabrication of electro-optic polymer modulators and switches
Optical Materials, 1999
Electro-optic polymers are interesting materials for realising active functions in integrated optics devices, since they can have relatively high electro-optic coefficients and they can be easily combined or integrated with several (passive) materials. Electro-optic interaction can be exploited for obtaining modulation or switching in polymer-based devices using several principles (e.g. Mach-Zehnder, Digital Optical Switch or tuned coupling to surface plasmons), which have been investigated and tested using a number of different materials. We compare these principles in view of several aspects of practical importance: realistic values of electro-optic coefficients and wavelength-dependent attenuation, optical, electrical and chemical compatibility of substrate, guiding and cladding layers, channel definition by etching (inverted) ridge waveguides or by photo-bleaching, local and global poling methods, polarisation-dependence, and the design of efficient high-bandwidth travelling wave electrodes. In most of the investigated devices, we employ a waveguiding structure based on silicon and its oxynitrides, exploiting the fact that the refractive index of silicon oxynitride can be accurately adjusted over a wide range by adjusting its composition. We will discuss the practical difficulties encountered and show the obtained results with phaseand intensity modulators and switches.
Polymer electro-optic modulators
2000
With the request for high speed data transmission through the införmation networks ever increasing, conventionallinks are being pushed to their limits. Optical interconnection can pro¬ vide the required bandwidth but there is a vital need to better merge optics with existing elec¬ tronic technologies, and to do so at a very low cost. Polymers are very promising for this integration of electronics and optics, especially in the encoding of införmation onto a light stream as this is a critical aspect of any interconnection scheme. Polymer electro-optic modulators are the main alternativeto the Standard Lithium niobatc based encoding approacb.es due to their intrinsic potential for ultrafast modulation, their low cost, and their ability for integration with semiconductor electronics. For polymer based electro-optic modulators. however, to replace current technologies. adequate performance and reliability has to be demonstrated. Materials with appropriate optical, chemical, and mechanical properties are needed and the modulator fabrication technology has to be mastered. The goal of this thesis is to investigate highly efficient and stable nonlinear optical molecules which offer the functionality to the polymers, and to fabricate electro-optic waveguide devicesbased on polyimide materials.
Electro-optic polymer based devices and technology for optical telecommunication
Comptes Rendus Physique, 2002
Electro-optic polymer waveguide devices are very attractive for optical communication systems, because of their potentially simple and low-cost fabrication procedure. High bandwidth devices are enabled by the low dielectric constant of polymers with negligible dispersion from DC to optical frequencies. We first detail the modelization steps relating to the optical and electrical aspects of devices. We then outline the different steps of the fabrication process of electro-optic polymer based devices. By way of illustrating these considerations, we present some original realizations namely polarization insensitive modulators, switching devices using an asymetric X coupler and optic to RF converters based on difference frequency mixing. To cite this article: P. Labbé et al., C. R. Physique 3 (2002) 543-554. 2002 Académie des sciences/Éditions scientifiques et médicales Elsevier SAS electro-optic polymers / integrated optics / devices / optical telecommunication Composants à base de polymères électro-optiques pour les télécommunications optiques Résumé * Correspondence and reprints.
Replica-molded electro-optic polymer Mach-Zehnder modulator
Applied Physics Letters, 2004
A Mach-Zehnder electro-optic polymer amplitude modulator is fabricated by a simple and high-throughput soft-stamp replica-molding technique. The modulator structure incorporates the highly nonlinear and stable chromophore, AJL8, doped in amorphous polycarbonate. Single-arm phase-retardation results in a halfwave voltage (Vπ) of 8.4 V at 1600 nm. The on/off extinction ratio is better than 19 dB, resulting from precise Y-branch power splitters and good waveguide uniformity. These results indicate that the simple fabrication process allows for good optical performance from high-fidelity replicas of the original master devices.
Optical Signal Processor Using Electro-Optic Polymer Waveguides
Journal of Lightwave Technology, 2000
We have investigated an optical signal processor using electro-optic polymer waveguides operating at a wavelength of 1.55 m. Due to recent developments, many useful optical devices have become available such as optical filters, modulators, switches, and multiplexers. It will be useful to have a single optical device, which is reconfigurable to implement all of these functions. We call such a device an "optical signal processor," which will play a similar role to digital signal processors in electrical circuits. We realize such an optical device in a planar lightwave circuit. Since the planar lightwave circuits are based on the multiple interference of coherent light and can be integrated with significant complexity, they have been implemented for various purposes of optical processing such as optical filters. However, their guiding waveguides are mostly passive, and the only viable mechanism to reconfigure their functions is thermal effects, which is slow and cannot be used for high-speed applications such as optical modulators or optical packet switches. On the other hand, electro-optic polymer has a very high electro-optic coefficient and a good velocity match between electrical and optical signals, thus, permitting the creation of high-speed optical devices with high efficiency. Therefore, we have implemented a planar lightwave circuit using the electro-optic polymer waveguides. As a result, the structure is complex enough to generate arbitrary functions and fast enough to obtain high data rates. Using the optical signal processor, we investigate interesting applications including arbitrary waveform generators.
Recent advances in polymer electro-optic modulators
In this brief review, nonlinear optical (NLO) chromophores widely used in electro-optic (EO) devices are summarized according to their EO coefficients. The advances of EO modulators based on organic materials in high bandwidth and low half wave voltages (V p ) are discussed. The review is mainly devoted to the following aspects: verification of high frequency operation and reduction of V p for all polymer waveguide EO modulators; (2) structures and advantages of sol-gel waveguide EO modulators; (3) principles and developments of silicon-organic hybrid (SOH) EO modulators. All the considerations are illustrated by the architecture of the devices and the used physical and chemical principles are explained in detail. Further means of improvement of their parameters are indicated.
New applications using single-sideband polymer electro-optic modulators
Proceedings of SPIE, 2003
New applications of optical single-sideband modulators incorporating multimode interference (MMI) structures have been investigated. These devices have been fabricated using recently developed polymer materials and advanced polymer modulator technologies. For the application of high-speed analog-to-digital conversion we have studied a photonic time-stretching system using the single-sideband modulator. This implementation has been shown to almost completely eliminate the power penalty due to the different chromatic dispersion effects, in upper and lower sidebands, without bandwidth limitations. We also have designed a photonic RF phase shifter array based on the single sideband modulator structure. In order to improve the performance, this integrated planar device has incorporated a novel balancing arm design, low crosstalk optical waveguide crossings and S-bend waveguide structures. Measurements of this configuration showed that our four outputs were independent and had highly linear RF phases with negligible RF power fluctuation. These pulsed and cw applications demonstrate the capability and complexity possible using polymer electrooptics and are expected to significantly contribute to future optical communication systems and to optical/microwave beam steering and transmission.
Science, 2000
Electro-optic (EO) modulators encode electrical signals onto fiber optic transmissions. High drive voltages limit gain and noise levels. Typical polymeric and lithium niobate modulators operate with halfwave voltages of 5 volts. Sterically modified organic chromophores have been used t o reduce the attenuation of electric field poling-induced electro-optic activity caused by strong intermolecular electrostatic interactions. Such modified chromophores, incorporated into polymer hosts, were used t o fabricate EO modulators with halfwave voltages of 0.8 volts (at a telecommunications wavelength of 1318 nanometers) and t o achieve a halfwave voltage-interaction length product of 2.2 voltcentimeters. Optical push-pull poling and driving were also used t o reduce halfwave voltage. This study, together with recent demonstrations of exceptional bandwidths (more than 110 gigahertz) and ease of integration (with very large scale integration semiconductor circuitry and ultra-low-loss passive optical circuitry) demonstrates the potential of polymeric materials for next generation telecommunications, information processing, and radio frequency distribution.
Monolithic integration of waveguide polymer electrooptic modulators on VLSI circuitry
IEEE Photonics Technology Letters, 2000
We demonstrated some of the critical technology that is needed for the monolithic integration of polymer electrooptic modulators and VLSI circuitry by fabricating and testing a phase slab modulator on nonplanar VLSI circuits. We demonstrated the survival of GaAs MESFET's to the high-voltage poling and polymer modulator fabrication procedures. We also implemented an electrical interconnect scheme between the electronics and photonics layers.
All-optical polymer waveguide devices
Materials and Devices for Optical and Wireless Communications, 2002
We fabricated all-optical polymer devices such as Mach-Zehnder modulator and 1x2 switch using a polymer doped with photoresponsive dyes. The refractive index change of the photoresponsive dyes by irradiation of light was utilized to fabricate switching and modulation devices. All-optical Mach-Zehnder modulator and switch are demonstrated which are composed of a polymer waveguide doped with the dyes in the core and a thick light blocking metal layer on the waveguide. The metal layer was opened on one arm of the Mach-Zehnder modulator and 1x2 Y-branch switch, so that only one arm could be irradiated by control light, thus allowing a changing of refractive index. The optical modulator and switch exhibited an extinction ratio of about -12 dB and a crosstalk of -14 dB at a wavelength of 1 .55 im respectively. A simple kinetic model developed to delineate the refractive index change in the dye doped polymer film was applied to predict the evolution of the modulation characteristics. We have also fabricated polymeric wavelength filters with Bragg grating. The surface relief grating was formed using an azobenzene polymer film and used as an etch mask to transfer the pattern to polymer waveguides by reactive ion etching (RIE). The grating period was 5OO nm and the depth was 3O nm with 10-mm-long grating length. A crosstalk of -20 dB at the Bragg wavelength and the 3-dB transmission bandwidth of 0.2 nm were obtained from the device.