Ultrafast all-optical chalcogenide glass photonic circuits.

Focus Serial: Frontiers of Nonlinear Optics

Broadband wavelength conversion at 40 Gb/s using long serpentine As(2)S(3) planar waveguides.

We demonstrate broadband wavelength conversion of a 40 Gb/s return-to-zero signal by cross-phase modulation in a newly developed chalcogenide glass waveguide based photonic chip. These new serpentine As(2)S(3) waveguides offer a nonlinear coefficient approximately 1700 W(-1)km(-1) with 5x lower propagation loss over a length of 22.5 cm which ensures the full propagation length contributes towards the nonlinear process. This reduces the peak operating power thereby allowing a x4 increase in the data rate compared with previous results. Spectral measurements show the device operates over a span of 40 nm while system measurements show just over 1 dB of power penalty at a bit-error rate of 10(-9). This is primarily due to the compact planar waveguide design which minimizes the effect of groupvelocity dispersion.

Error free all optical wavelength conversion in highly nonlinear As-Se chalcogenide glass fiber.

We present the first demonstration of all optical wavelength conversion in chalcogenide glass fiber including system penalty measurements at 10 Gb/s. Our device is based on As2Se3 chalcogenide glass fiber which has the highest Kerr nonlinearity (n(2)) of any fiber to date for which either advanced all optical signal processing functions or system penalty measurements have been demonstrated. We achieve wavelength conversion via cross phase modulation over a 10 nm wavelength range near 1550 nm with 7 ps pulses at 2.1 W peak pump power in 1 meter of fiber, achieving only 1.4 dB excess system penalty. Analysis and comparison of the fundamental fiber parameters, including nonlinear coefficient, two-photon absorption coefficient and dispersion parameter with other nonlinear glasses shows that As(2)Se(3) based devices show considerable promise for radically integrated nonlinear signal processing devices.

All optical wavelength conversion via cross phase modulation in chalcogenide glass rib waveguides.

We demonstrate all-optical wavelength conversion in a 5 cm As(2)S(3) chalcogenide glass rib waveguide with 5.4 ps pulses over a wavelength range of 10 nm near 1550 nm. We present frequency resolved optical gating (FROG) measurements that show good converted pulse integrity in terms of amplitude and phase in the frequency and time domains. The short interaction length ensures that dispersion induced walk-off does not hinder the conversion range of the device.

Integrated all-optical pulse regenerator in chalcogenide waveguides.

We report a fully integrated, passive, all-optical regenerator capable of terabit per second operation, based on a highly nonlinear chalcogenide (As2S3) glass rib waveguide followed by an integrated Bragg grating bandpass filter. We demonstrate a clear nonlinear power transfer curve with 1.4 ps optical pulses, capable of improving the signal-to-noise ratio and reducing the bit error rate for digital signals.

Microstructured optical fiber photonic wires with subwavelength core diameter.

We demonstrate fabrication of robust, low-loss silica photonic wires using tapered microstructured silica optical fiber. The fiber is tapered by a factor of fifty while retaining the internal structure and leaving the air holes completely open. The air holes isolate the core mode from the surrounding environment, making it insensitive to surface contamination and contact leakage, suggesting applications as nanowires for photonic circuits . We describe a transition between two different operation regimes of our photonic wire from the embedded regime, where the mode is isolated from the environment, to the evanescent regime, where more than 70% of the mode intensity can propagate outside of the fiber. Interesting dispersion and nonlinear properties are identified.

Higher order mode conversion via focused ion beam milled Bragg gratings in Silicon-on-Insulator waveguides.

We report the first Bragg gratings fabricated by Focused Ion Beam milling in optical waveguides. We observe striking features in the optical transmission spectra of surface relief gratings in silicon-on-insulator waveguides and achieve good agreement with theoretical results obtained using a novel adaptation of the beam propagation method and coupled mode theory. We demonstrate that leaky Higher Order Modes (HOM), often present in large numbers (although normally not observed) even in nominally single mode rib waveguides, can dramatically affect the Bragg grating optical transmission spectra. We investigate the dependence of the grating spectrum on grating dimensions and etch depth, and show that our results have significant implications for designing narrow spectral width gratings in high index waveguides, either for minimizing HOM effects for conventional WDM filters, or potentially for designing devices to capitalize on very efficient HOM conversion.