350 research outputs found
Single integrated device for optical CDMA code processing in dual-code environment
We report on the design, fabrication and performance of a matching integrated optical CDMA encoder-decoder pair based on holographic Bragg reflector technology. Simultaneous encoding/decoding operation of two multiple wavelength-hopping time-spreading codes was successfully demonstrated and shown to support two error-free OCDMA links at OC-24. A double-pass scheme was employed in the devices to enable the use of longer code length
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Novel printing technologies for nanophotonic and nanoelectronic devices
textAs optical interconnects make their paces to replace traditional electrical interconnects, implementing low cost optical components and hybrid optic-electronic systems are of great interest. In the research work described in this dissertation, we are making our efforts to develop several practical optical components using novel printing technologies including imprinting, ink-jet printing and a combination of both. Imprinting process using low cost electroplating mold is investigated and applied to the waveguide molding process, and it greatly reduces the surface roughness and thus the optical propagation loss. The imprinting process can be applied to photonic components from multi-mode waveguides with 50[mu]m critical dimension down to photonic crystal structures with 500nm hole diameter. Compared to traditional lithography process, imprinting process is featured by its great repeatability and high yield to define patterns on existing layers. Furthermore we still need an approach to deposit layers and that is the reason we integrate the ink-jet printing technology, another low-cost, low material consumption, environmental friendly process. Ink-jet printing process is capable of depositing a wide range of materials, including conductive layer, dielectric layer or other functional layers with defined patterns. Together with molding technology, we demonstrate three applications: proximity coupler, thermo-optic (TO) switch and electro-optic (EO) polymer modulator. The proximity coupler uses imprinted 50[mu]m waveguide with embedded mirrors and ink-jet printed micro-lenses to improve the board-to-board optical interconnects quality. The TO switch and EO modulator both utilize imprinting technology to define a core pattern in the cladding layer. Ink-jet printing is used to deposit the core layer for TO switch and the electrode layers for EO modulator. The fabricated TO switch operates at 1 kHz with less than 0.5ms switching time and the EO modulator shows V[pi][middle dot]L=5.68V[middle dot]cm. To the best of our knowledge, these are the first demonstrations of functional optical switches and modulators using printing method. To further enable the high rate fabrication of ink-jet printed photonic and electronic devices with multiple layers on flexible substrate, we develop a roll-to-roll ink-jet printing system, from hardware integration to software implementation. Machine vision aided real time automatic registration is achieved when printing multiple layers.Electrical and Computer Engineerin
Design and Development of an Optical Chip Interferometer For High Precision On-Line Surface Measurement
Advances in manufacturing and with the demand of achieving faster throughput at a lower cost in any industrial setting have put forward the need for embedded metrology. Embedded metrology is the provision of metrology on the manufacturing platform, enabling measurement without the removal of the workpiece. Providing closer integration of metrology upon the manufacturing platform will improve material processing and reliability of manufacture for high added value products in ultra-high-precision engineering. Currently, almost all available metrology instrumentation is either too bulky, slow, destructive in terms of damaging the surfaces with a contacting stylus or is carried out off-line. One technology that holds promise for improving the current state-of-the-art in the online measurement of surfaces is hybrid photonic integration. This technique provides for the integration of individual optoelectronic components onto silicon daughter boards which are then incorporated on a silica motherboard containing waveguides to produce a complete photonic circuit.
This thesis presents first of its kind a novel chip interferometer sensor based on hybrid integration technology for online surface and dimensional metrology applications. The complete metrology sensor system is structured into two parts; hybrid photonic chip and optical probe. The hybrid photonic chip interferometer is based on a silica-on-silicon etched integrated-optic motherboard containing waveguide structures and evanescent couplers. Upon the motherboard, electro-optic components such as photodiodes and a semiconductor gain block are mounted and bonded to provide the required functionality. Optical probe is a separate entity attached to the integrated optic module which serves as optical stylus for surface scanning in two measurement modes a) A single-point for measuring distance and thus form/surface topography through movement of the device or workpiece, b) Profiling (lateral scanning where assessment of 2D surface parameters may be determined in a single shot. Wavelength scanning and phase shifting inteferometry implemented for the retrival of phase information eventually providing the surface height measurement. The signal analysis methodology for the two measurement modes is described as well as a theoretical and experimental appraisal of the metrology capabilities in terms of range and resolution.
The incremetal development of various hybrid photonic modules such as wavelength encoder unit, signal detection unit etc. of the chip interferometer are presented. Initial measurement results from various componets of metrology sensor and the surface measurement results in two measurement modes validate the applicability of the described sensor system as a potential metrology tool for online surface measurement applications
Design of weak 1-D bragg grating filters in SOI waveguides using volume holography techniques
To answer the growing need for more versatile integrated spectral filters, we show that weak one-dimensional gratings can be designed towards any desired target spectrum. We follow a very straightforward design procedure to demonstrate the performance of these devices. Measurements and simulations show a very good correspondence with the target spectra. By analyzing the results, we also found that the design procedure can be refined by using simulated reflections, instead of relying on the calculated Fresnel reflections
Optical-CDMA in InP
This paper describes the InP platforms for photonic integration and the development on these platforms of an optical code division multiple access (O-CDMA) system for local area networks. We demonstrate three building blocks of this system: an optical pulse source, an encoder/decoder pair, and a threshold detector. The optical pulse source consists of an integrated colliding pulse-mode laser with nearly transform-limited 10 Gb/s pulses and optical injection locking to an external clock for synchronization. The encoder/decoder pair is based on arrayed waveguide gratings. Bit-error-rate measurements involving six users at 10 Gb/s showed error-free transmission, while O-CDMA codes were calibrated using frequency resolved optical gating. For threshold detection after the decoder, we compared two Mach--Zehnder interferometer (MZI)-based optical thresholding schemes and present results on a new type of electroabsorber-based MZI
Monolithically integrated mode-locked ring lasers and Mach-Zehnder interferometers in AlGaInAs
In this thesis, monolithically integrated photonic devices for next generation optical
telecommunications networks were investigated, namely semiconductor modelocked
ring lasers and Mach-Zehnder interferometers operating at 1550 nm. Fabricated
on the aluminium quaternary, the 2.3mm long passively mode-locked ring
devices produced 1 ps pulses at a repetition rate of around 36GHz. It was found
that the symmetrically placed dual saturable absorber configuration lead to the
largest area of stable mode-locking, agreeing well with theoretical predictions in
the literature. Optical harmonic injection mode-locking was found to improve the
pulse timing stability, with a reduction in the radio frequency 3 dB linewidth from
1.4MHz down to 108 kHz, indicating a vast improvement in timing jitter. The
sputtered SiO2 quantum-well intermixing technique allowed for the realisation of
both symmetric and asymmetric arm length Mach-Zehnder interferometers, which
were demonstrated as an electro-optic switch, tunable wavelength filter and optical
code division multiple access encoder/decoder. The work concluded with the
monolithic integration of a mode-locked ring laser and asymmetric Mach-Zehnder
interferometer to demonstrate a simple, yet effective, photonic integrated circuit
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