Payam Rabiei

Polymer micro-ring filters and modulators

Micro-ring wavelength filters and resonant modulators using polymer materials at 1300 nm and 1550 nm are analyzed, designed, and demonstrated. The rings are integrated with vertically coupled input and output waveguides. The devices are fabricated using optical lithography. Filters with a finesse of 141 and free spectral range of 5 nm at 1300 nm and finesse of 117 with a free spectral range (FSR) of 8 nm at 1550 nm are demonstrated. Ring resonators with a Q as high as 1.3 /spl times/ 10/sup 5/ at 1300 nm are demonstrated. The filters can be temperature tuned at the rate of 14 GHz//spl deg/C. Resonant ring modulators, which use an electrooptic polymer, are demonstrated. The resonance wavelength voltage tunes at the rate of 0.82 GHz/V. The modulators have a bandwidth larger than 2 GHz. Using the resonant modulator, and open eye diagram at 1 Gb/s is demonstrated.

Lithium niobate ridge waveguides and modulators fabricated using smart guide

Ridge waveguides are fabricated using submicron thin films of lithium niobate prepared by crystal ion slicing and wafer bonding (“smart guide”). The waveguides are made by physical etching the lithium niobate thin film using ion beam milling. The waveguides are low loss. An electro-optic polarization modulator with VπL of 15Vcm at λ=1.55μm is demonstrated using the waveguides.

Tunable polymer double micro-ring filters

Based on the vernier effect, widely tunable polymer double micro-ring filters using the thermooptic effect or the electrooptic effect are demonstrated. A tuning enhancement factor of 40 was achieved at wavelengths near 1550 nm. The tuning rate for the thermooptic device is 120 GHz/mW and for the electrooptic device is 120 GHz/12 V. A tunable laser with a side-mode suppression ratio greater than 30 dB was demonstrated using this filter and erbium-doped fiber amplifier gain. Thermal tuning over 35 nm was achieved.

Model order reduction of large circuits using balanced truncation

A method is introduced for model order reduction of large circuits extracted from layout. The algorithm, which is based on balanced realization, can be used for reducing the order of circuits before circuit-level simulation. In contrast to Pade-based algorithms which match the reduced order system with original system in some given frequencies, balanced realization based model algorithms provide a nearly optimal matching over all frequencies. Hence the balanced realization method produces stable and more accurate results compared to the Pade-based algorithms for model reduction. In addition given an upper bound for error, it is possible to compute the minimum degree for the reduced order model a priori. A numerically efficient method for balanced truncation of large circuits using the Arnoldi algorithm is presented and experimental results are reported.

Second harmonic generation of 2.6W green light with thermoelectrically oxidized undoped congruent lithium niobate crystals below 100°C

We demonstrate that thermoelectric oxidization suppresses unwanted light-induced refractive index changes in undoped congruent periodically poled lithium niobate crystals used for single-pass continuous-wave frequency doubling of 1030nm light. The maximum second harmonic output power shows a strong dependence on the phase matching temperature. For 90°C, a total of 2.6W green light is generated with an efficiency of 22% corresponding to a normalized conversion efficiency of 1.8%∕W.

Analysis of hybrid optoelectronic WDM ADC

A new hybrid optoelectronic wavelength-division demultiplexed (WDM) architecture to extend electronic analog-to-digital conversion (ADC) performance is analyzed and simulated. Mode-locked optical pulses are amplitude-modulated by an RF signal and optically demultiplexed into a number of parallel channels. The signal in each channel is converted to an electrical signal and then passed through a simple low-pass filter. The effect of low-pass filter response, filter matching, noise due to jitter, and detector shot noise on system performance is simulated.

Calculation of losses in micro-ring resonators with arbitrary refractive index or shape profile and its applications

A perturbative approach is discussed for the calculation of the radiation and scattering losses in cylindrical microresonators with arbitrary refractive index or shape profile. A new method for inducing losses in the cavity using the electrooptic effect with periodic modulation of the refractive index is introduced. The perturbative method is used for the calculation of the losses due to periodic modulation of the refractive index. The applications of this approach for the calculation of scattering losses due to surface roughness of microresonators and scattering due to deviation from ideal cylindrical shape are discussed.

Integrated WDM polymer modulator

DWDM systems require many lasers and modulators to generate the required optical signals to be transmitted. Previously micro-ring resonators were considered as filters and lasers in WDM systems. In an effort to integrate and minimize the cost of WDM systems modulators we have demonstrated a novel wavelength sensitive modulator based on micro-ring resonator. Conventional electro-optic modulators are based on Mach-Zehnder interferometer. Recently high performance Mach-Zehnder modulators using polymer electro-optic materials have been demonstrated. We have used the same polymers for high-speed wavelength selective modulation using micro-ring structure.

Polymer micro-ring modulator with 1 THz FSR

Polymer microring modulators with FSR larger than 1 THz, modulation bandwidth of 15 GHz and the fall with half maximum voltage of 20 V are demonstrated at 1300 nm. Multi-wavelength modulation with a total bandwidth of 400 Gb/s is practical.

Organic electro-optic materials: some unique opportunities

Recent use of quantum mechanics to guide the improvement of molecular hyperpolarizability and the use of statistical mechanical analysis of the effects of intermolecular electrostatic interactions to improve the acentric ordering of organic chromophores has led to the realization of electro-optic coefficients, r33, greater than 100 pm/V (at telecommunication wavelengths). This material design and development paradigm is likely to lead to further improvement in electro-optic activity, which will in turn facilitate the development of a variety of electro-optic devices with drive (Vπ) voltage requirements of less than one volt. The utility of organic electro-optic materials for development of high bandwidth devices is now well documented. What is less obvious is the utility of organic electro-optic materials for the fabrication of complex (including conformal, flexible, and three-dimensional) device structures. In this communication, we review recent improvements in electro-optic activity; thermal and photochemical stability; and processability of organic electro-optic materials and the use of these materials to fabricate conformal and flexible electro-optic devices and devices based upon single and multiple coupled ring microresonators.