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Research On Integrated All-Optical-Wavelength-Conversion And All-Optical-Signal-Processing Devices

Posted on:2017-04-23Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y C WuFull Text:PDF
GTID:1108330491962886Subject:Optical communication technology
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The rapid growth of the internet and internet-related services calls for a networking with larger capacity and higher communication speed than ever before. Based on the Wavelength-Division-Multiplexing (WDM) or Dense-Wavelength-Division-Multiplexing (DWDM) technology, optical fiber can provide huge bandwidth. However, when the optical data packages reach the net node or data center, they will be downloaded from the fiber and then demuxed, retimed, reshaped, regenerated. After all these data processing procedures, which mostly need an Optical-Electrical-Optical (O-E-O) conversion, the optical data packages will be routed to the next link. Thus, the electrical bottle neck is the fatal restriction of network bandwidth. All optical communication is a cutting edge research topic, aims at making optical data processing realized at optical level, so as to get a larger bandwidth as well as a tighter net framework with a much lower power consumption. This dissertation focuses on all optical data processing, based on the cross modulation inside semiconductor optical amplifier (SOA) and injection-locking phenomenon of laser diodes, presents both theory, numerical simulation and experimental results of all optical wavelength conversion and optical flip-flop memory.V-cavity laser (VCL) consists of a half-wave coupler and two cavity with a slight length difference. Based on the Vernier effect, the laser can cover a wide tuning range with very high side-mode suppression ratio (SMSR). Because no grating structure is adopted in VCL, the fabrication procedure is compatible with other waveguide components. In this dissertation, we proposed a delayed-interferometer Mach-Zehnder interferometer (DI-MZI) based all optical wavelength converter (AOWC). All the devices are monolithically integrated on offset quantum well III-V wafer, including VCL as continues wavelength (CW) laser, delay waveguide, multi-mode interference coupler (MMI), SOAs, tapers, and so on. Our design can achieve 10 Gb/s non-return to zero (NRZ) data wavelength conversion with an extinction ratio of over 10 dB. Using this AOWC structure as a building block, we propose an all optical routing system for fiber-to-fiber channel switch.Thanks for the mature CMOS technique, low cost as well as high refractive index difference, Si is always considered as an ideal platform for passive light circuit. It is desired to have III-V on Si so as to have active and passive components integrated on one chip. Using DVS-BCB adhesive layer bonding technique, we successfully demonstrated single SOA achieved 12.5 Gb/s NRZ wavelength conversion and get clear open eye diagrams at 40 Gb/s. The active part of total device is only 500 um and consumes less than 250 mW. The power penalty at 40 Gb/s is less than 3 dB with a bit error rate below 10-5. The wavelength conversion range covers 1545 nm to 1560 nm.Apart from fiber communication area, optical method is also popular in micro-wave communication to make the system more efficient and less complex. Dual-wavelength laser can generate THz carrier signal. Comparing with wireless medium, Radio over Fiber (RoF) attenuates much less and will travel further. In this dissertation, we propose a novel dual-wavelength laser based on SOI hybrid integration platform. We use the grating micro-ring (GMR) as the front reflector of the laser. A single mode symmetric splitting in reflection spectrum appears when embedding shoulder gratings inside a micro-ring resonator. By adjusting the reflection coefficient of the gratings and the coupling coefficient between the ring and the straight waveguide, the difference between the two lasing wavelengths can vary from 0 to more than 1nm.When SOA is used for cross modulation application, it is working in saturation region with a large biase current and the injected optical signal also need a pre-amplification. Here comes the thermal issues, which becomes more serious when several active devices integrated together. To make the chip more compact with even lower power consumption, we present an injection-locking based wavelength conversion inside VCL. We got 2.5 Gb/s NRZ wavelength conversion with 200 GHz channel spacing and the ER is more than 4 dB, side-mode suppression ratio (SMSR) is more than 36 dB.Through optimizing the design of VCL, a bistable region in the tuning characteristics of the VCL is discovered. When the VCL is biased in the middle of hysteresis loop, its working state can be controlled by injecting signal pulses at the two wavelengths, so is to achieve the flip-flop operation. The pulse power for both set and reset signal is only about 1 pJ. Short response times of about 150 ps are measured for storing and erasing.
Keywords/Search Tags:High speed, all optical wavelength conversion, semiconductor optical amplifier, integrated optics, silicon photonics
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