Top PDF Integrated Ultra-High-Q Nonlinear Photonic Platform for On-Chip Optoelectronic Systems

Integrated Ultra-High-Q Nonlinear Photonic Platform for On-Chip Optoelectronic Systems

Integrated Ultra-High-Q Nonlinear Photonic Platform for On-Chip Optoelectronic Systems

mode waveguide coupler. However, the mode coupling is only 25 % level so that might not be sufficient to use the coupling for nonlinear optics application – generally coupling strength also determines operating power of both frequency comb and lasers[22, 55]. Besides, TM0 mode has higher Q 0 , but it is even not coupled with straight nitride waveguide because of insufficient field overlap between TE waveguide mode and quasi-TM resonator mode. In order to strengthen the mode coupling with fundamental modes, cavity-waveguide gap can be one of methods that adjust the magnitude of field overlap. This approach corresponds to the gap adjustment between taper fiber and WGM resonator, and it can cause an additional scattering loss because then waveguide needs to be on the outward sidewall of the ridge resonator. Pulley waveguide structure[4] is also another approach, and this method can avoid an additional scattering loss caused in narrower gap. Fig.5.20 shows optical microscope image of pulley nitride waveguide featured on integrated resonator system. As has been discussed in 5.4.3, the width of nitride waveguide is constant in the bending region so as to keep the same phase-matching condition with longer interaction length. The designed waveguide dimension is same with the straight waveguide (900 nm × 250 nm).
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Integrated Nonlinear Photonic Devices

Integrated Nonlinear Photonic Devices

The waveguide geometry is shown in Figure 6.2 and features a silica ridge design that is air-clad on three sides. The air-cladding enables a high level of optical confinement to both increase the optical nonlinearity and shift the wavelength for zero group velocity dispersion towards visible wavelengths. The fabrication of the waveguides is similar to the process used for the integrated ultrahigh-Q silica ridge ring resonator (see Chapter 2). The process flow is presented in Figure 6.3. Waveguide arrays are fabricated on (100) prime-grade float-zone silicon wafers. The initial oxide layer is thermally grown at 1000 ◦ C with 2 µm thickness. The photoresist is patterned on the oxide layer (Figure 6.3a), and acts as etch mask during hydrofluoric acid (HF) immersion. HF wet-etching creates the wedge surfaces at the edge of the photoresist pattern, and the further wet-etching results in the triangular- cross-section ridge stripe of silica as the two angled wedge surfaces meet each other (Figure 6.3b). The wet-etching duration is around 45 min. Then, an additional thermal oxidation creates an under-layer of silica (Figure 6.3c). The waveguide chips used for data in this chapter had the under-layer thickness of either 310 nm or 450 nm. Striped openings (Figure 6.3d) are etched after a second lithography step (Figure 6.3e). As a final step, the silicon under the oxide structure is isotropically etched (Figure 6.3f). Both numerical calculation and measurement confirmed that an undercut of 10 µm is sufficient to eliminate the silicon structure interaction as a result of modal confinement. The average spacing between two waveguides is about 35 µm, and 725 waveguides per inch can be fabricated in an array.
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On chip optoelectronic feedback in a micropillar laser detector assembly

On chip optoelectronic feedback in a micropillar laser detector assembly

In conclusion, optoelectronic feedback using a QD-based, monolithically integrated microlaser-microdetector assembly has been realized and investigated experimentally as well as theoretically. Self- pulsing of the microlaser was observed over a narrow range of laser biases, and the system was modelled with rate equations in dependence of cavity photon number, charge carrier number and a temperature dependence of the microlaser gain qualitatively reproducing the experimental results. We find that the inclusion of thermal effects is necessary to describe the observed µs modulation of the laser output under feedback. With further development, our platform could be employed for diverse applications such as tuning the external cavity geometry to match the laser excitation, forming an integrated resonant detection device with a higher efficiency and potential use for in-situ monitoring. Integration of amplifier electronics on the same chip would comprise a truly self-contained, on-chip feedback system for compact chaotically secure communication [24] or for an array of self-pulsed single-photon source when utilizing one or more external micropillars as a quantum light emitter instead of as a photodetector. Also, a network of nonlinear oscillators could be conceived for studying complex nonlinear dynamics [25]. Further work is required to optimize the
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On Radioactivity–Exposed Nanophotodetector Optoreliability

On Radioactivity–Exposed Nanophotodetector Optoreliability

tion-zone (by a cumulative occupation probability of [1 – exp (–αW)] with α being the depletion-zone material absorption-coefficient for the specific illumition wavelen -grh and W the depletion-zone width valid for the value of reverse bias applied to the sensor under testing, deriv- ing as the difference between probability of photonic entrance into and probability of photonic exit from the depletion-zone extension under the assumption of shal- low depletion-zone, materialising for the technologically conventional photodetectors, like the commercial p-i-n photodiodes) and, furthermore, succeed (by a quantum efficiency of F corresponding to the specific illumina- tion-wavelength) in being absorbed within the depletion zone, ultimately energetically liberating initially bound (in the semiconductor valence-band or at impurity or lattice-defect trap-levels) charge carriers:
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A Survey on Energy Harvesting in Wireless Communication

A Survey on Energy Harvesting in Wireless Communication

Mechanical energy gathering devices produces electricity from vibration, stress and strain. Energy extraction from vibrations is predicated on the movement of a spring mounted mass relative to its support frame. Mechanical acceleration is created by vibrations that successively cause the mass element to maneuver and oscillate (Kinetic energy).This energy may be regenerate into electricity via strain on a piezoelectric material which implies there's a peak frequency at that system derives most of its energy. Piezoelectric material has the distinctive property of manufacturing an electrical charge once bear a mechanical strain and the other way around once electrical potential is applied. Piezo electrical material receives the foremost quantity of analysis attention thanks to their high voltage, easy implementation, and their suitability. The piezo electrical material Lead metal Titan ate (PZT) exhibits a comparatively high conversion of mechanical to electricity. Innovative energy gather technology will collect vibration from the setting and convert them into electricity to power a range of sensors. several of the vibrations in natural and manmade setting tare comparatively low frequency (under 120Hz),and often rely on energy sources of variable activity levels like engine vibrations, wind level, vehicle speed, etc. The output power of a vibration driven energy harvester is directly proportional to the vibration amplitude and frequency of the energy supply, and therefore the size of the harvester. The number of electricity generated by vibration will increase the output by increasing the frequency and amplitude of the vibrator. Once a piezoelectric system vibrates at its resonance frequency, even a tiny low actuation will cause giant displacement amplitudes. Strain or deformation in an exceedingly piezoelectric material causes charge separation across the device manufacturing an electrical field and consequently a free fall proportional to the strain applied. Figure 1 shows the Energy harvesting diagram for sensor network.
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Design of Ultra Low Loss Highly Nonlinear Dispersion Flattened Octagonal Photonic Crystal Fibers

Design of Ultra Low Loss Highly Nonlinear Dispersion Flattened Octagonal Photonic Crystal Fibers

in the form of periodic array of air-holes in either circular or in elliptical shape which might be in the form of hexagonal pattern. This will result in the periodic variation in refractive index around the fiber-core running down its length and the first PCF proto-type was reported in 1996 [2]. The most attractive feature of PCFs is the flexibility in designing the micro-structures (Photonic band gaps) in the dielectric material. This is the most im- portant factor that determines the characteristic behavior of interaction between the photons and the dielectric material. It is possible to tune the wavelength range in PCFs by the geometry of periodic dielectric variations [11] [12]. The dimensions of the micro-structured elements are of the order of light wavelength propagating through the fiber. One can design micro-structures in optical materials so that propagation of light over certain range of frequencies can be inhibited and some other bands of frequencies can be allowed to propagate [13]-[15]. It can be seen the behavior of photons in periodically micro-structured dielectric materials and that of electrons in crystalline semiconductors are similar [16].
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Optical Conductivity and Dielectric Response of an Organic Aminopyridine NLO Single Crystal

Optical Conductivity and Dielectric Response of an Organic Aminopyridine NLO Single Crystal

In recent years, researchers devoted much attention to nonlinear photonic crystals as their use in photonic band gap materials for controlling and molding the flow of light. The growth of research in nonlinear optics (NLO) is closely linked to the rapid technological advances that have occurred in related fields such as ultra-fast phenomena, optical communication and optical storage devices [1]. Organic nonlinear optical crystals which possess a good second harmonic generation efficiency due to their high optical band gap and low dielectric constant are in rich demand in optical storage devices, colour display units and optical communication systems etc [2]. It has been already reported that the pyridinium acceptor shows large second harmonic nonlinearity [3]. Recently optical properties of aminopyridine complexes and its suitability for the optoelectronic devices fabrications were reported [4, 5]. In the present work, we have made an analysis of electro-optical properties correlated with dielectric properties of 2-aminopyridine 4-aminobenzoate single crystal.
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An Ultra Wideband Impulse Optoelectronic Radar: Rugbi

An Ultra Wideband Impulse Optoelectronic Radar: Rugbi

At the same time, high power electronic generators are developed with less and less important trigger jitter. For example, available on the market, fast power generator delivering pulses with amplitude of 50 kV, rise time less than 200 ps, with a repetition frequency of 1 kHz presents a trigger jitter less than 20 ps. The integration of such a generator in a multi element system becomes possible when the highest spectral frequency of the radiation pulse is less than 2 GHz.

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On-chip photonic label-free biosensors

On-chip photonic label-free biosensors

total scan range of 0.4 nm. For resonators of small radii, this range is less than the FSR, and it is possible that no resonance is detected. Luckily, in such cases, it is possible to move the center of the fine scan window with the motor actuator, until one resonance becomes visible. e second issue is the need of the two photodetectors, that inevitably reduces the light power made available to probe the WGM resonator. When the insertion losses of the photonic chip are high, this can be a problem. e third issue, and probably the more serious, is that the LiON laser shows many mode-hops. Despite the specification of the constructor and the particular precautions in the design of the cavity, Figure 2.10(a), we observed an unpredictable number, from 5 to 20 or more, of mode-hops in the 0.4 nm range of the fine scan. With resonances of ≈ 50 pm width, it is quite probable that, sooner or later, the resonance will cross the spectral position of one of these mode- hops. Figure 2.14(b) shows the apparent hops in resonance position when this happens. e effective shift, caused by the mode-hops, is in the order of 3 pm. Being an apparent shift, and, in addition, a quite visible artefact, it should be possible to correct the data in post- processing. However, for a better reliability of the resonance shift measurement, any mode-hop should be avoided from the beginning.
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Silicon nitride photonics for the near infrared

Silicon nitride photonics for the near infrared

As the data traffic increases, current telecommunications are approaching the capacity limit of conventional single mode fibres that operate in the O and C wavelengths bands. As a result, there is an increasing interest in wavelength ranges in which new technologies can be implemented to help overcome this limitation. The 2 µm wavelength range has received particular attention as it benefits from the emergence of thulium-doped fibre amplifiers and hollow-core photonic bandgap fibres whose gain window and low loss (0.1 dB/km) is centred around 1900-2100 nm [76]–[78]. In this context, silicon nitride is a material that has potential for applications in this new wavelength regime as it is transparent well within the limits of the 2 µm wavelength band. In addition, it has the potential to exhibit a low thermo-optic coefficient and low propagation losses which are essential to demonstrate efficient devices with high tolerance to temperature variations.
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Ultra Sharp Photonic Bends: A Review

Ultra Sharp Photonic Bends: A Review

Silicon has been for many years the base material for microelectronic devices. Silicon photonics is the study and application of photonic systems which use silicon for optical switching and optical waveguide for data transfer. Silicon photonic devices are considered because Si is abundantly available and devices can be made using existing semiconductor fabrication techniques. An additional advantage for using Si is the high refractive index which is helpful in attaining high refractive index contrast for the confinement of light within the waveguide as shown in Fig.1 so to utilize the advantages of both hybrid devices are used.
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An Integrated Optofluidic Platform Enabling Total Phosphorus On-Chip Digestion and Online Real-Time Detection

An Integrated Optofluidic Platform Enabling Total Phosphorus On-Chip Digestion and Online Real-Time Detection

The design and 3D diagram of the integrated optofluidic device are shown in Figure 1a. It mainly consists of three functional parts: The first one is a spiral hollow optical fiber (Figure 1a inset) with the total length of 27 cm and inner diameter of 100 µm as a microchannel for the phosphorus digestion reaction; the second part is a PDMS-based micromixer for the chromogenic reaction; finally, the optical detection part is composed by a Z-shaped flow cell and a couple of optical fiber collimators. All the above functional parts are fixed on a glass slide (7.5 cm × 3 cm). A miniature heater (3 cm × 3 cm) is placed under the spiral hollow optical fiber to construct a high temperature and high pressure surrounding for phosphorus digestion reaction. When the aqueous phosphorus samples and oxidant are simultaneously injected into the hollow optical fiber in proportion by a syringe pump, the heater supplies enough heat quantity and pressure for the digestion reaction while avoiding gas bubble generation. For the part of chromogenic reaction, chromogenic agent A (ascorbic acid solution) and chromogenic agent B (ammonium molybdate solution, concentrated sulfuric acid and antimony potassium tartrate solution) are injected into the micromixer and reacts with the digested samples. Here, the micromixer is designed with typical convergent–divergent walls with the microchannel height of 150 µm [14]. Finally, the chromogenic samples are transferred to the Z-shaped flow cell for optical absorption detection.
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Article Ultra-Low-Loss Silicon Waveguides for Heterogeneously Integrated Silicon/III-V Photonics

Article Ultra-Low-Loss Silicon Waveguides for Heterogeneously Integrated Silicon/III-V Photonics

The ring in Figure 5a has a 750 µm bend radius, for which we did not observe any bend-loss induced radiation in the resonator. To confirm this, we investigated rings with varying radii, and plot their intrinsic Q factor alongside the theoretical bend-loss limit for Q in Figure 5b. The experimental results are extracted from the measured FWHM, while the dashed lines are simulated using Lumerical MODE solutions. The simulations are shown for three different etch depths, as that is the most sensitive parameter to the bend-loss. We find that our ring in this experiment is actually overetched compared to the target 56 nm, judging by the Q of the smaller rings. We do not observe significant bend loss in the rings until the radius is less than 550 µm. For practical reasons, the ring radius should be larger than 700 µm to avoid bend-loss possibly caused by an underetch of the waveguide.
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Photonic crystal interfaces: a design driven approach

Photonic crystal interfaces: a design driven approach

Having designed and fabricated devices, the next step is characterisation. There are two major measurement techniques used in this thesis. The first, analysis of the efficiency of surface grating couplers using the fibre to fibre coupling, is straightforward in principle, although the number of devices which must be fabricated successfully to complete this analysis is large, and hence demanding. The second is a more complex interferometric method, which yields useful data from a smaller set of devices. The end-to-end transmission spectrum is recorded at very high resolution, and then Fourier transformed to exploit the round-trip signature on the Fabry-Perot fringes. This allows us to calculate the loss due to the PhC, and also determine the points in the device where reflections occur, indicating impedance mismatches which must impair the device efficiency. Using these two methods, I have shown two separate cases - InP surface grating couplers and AlGaAs routing elements - that I have been involved in fabricating, operating very close to their designed levels, and thus validating the design.
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High-speed and Robust Integrated Silicon Nanophotonics for On-Chip Interconnects

High-speed and Robust Integrated Silicon Nanophotonics for On-Chip Interconnects

Efficient optical interconnects are one of the most promising application of Silicon photonics [94], [95]. The fundamental element of any optical interconnect is the electro- optic modulator, and there have been many successful demonstrations of amplitude based silicon modulators [94], [95]. However, phase encoded modulation has been required for the advancement of all communication technologies. For example, while amplitude modulation was used in optical fiber communications for decades, by the beginning of the last decade there was a rapid transition to phase based encodings due to the exponentially increasing bandwidth requirements of the internet [93]. Silicon photonics is experiencing a similar demand for bandwidth and will also need to move towards using phase encodings [94], [95]. There are several reasons that phase modulation is preferred over amplitude modulation: (1) Maximization of signal/noise; (2) Minimization of nonlinear effects; (3) Maximization of channel efficiency (which translates to increased system bandwidth).
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Electronic and Photonic Band Engineering for Novel Optoelectronic and Nanophotonic Devices

Electronic and Photonic Band Engineering for Novel Optoelectronic and Nanophotonic Devices

conductor compounds, these nitrides have attracted more and more interest in the opto- electronic applications. The direct bandgap of III-nitride is one of their most beneficial features for optoelectronic device applications. Moreover, the nitride alloys are particularly attractive since the bandgaps of aluminum nitride (AlN), gallium nitride (GaN) and indium nitride (InN) are 6.2 eV, 3.44 eV and 0.76 eV [1] at 300 K respectively and they cover the entire visible wavelength spectrum. In addition, the wide bandgap found in GaN, AlN and their compounds results in a low intrinsic carrier density which in turn leads to low voltage and low dark current, especially important for photodetectors and high-temperature elec- tronics. III-nitrides also have high melting points and mechanical strength. Adding to the list, the infra-red resistance to radiation damage yields a material system suitable for high frequency, high power and high temperature applications. In addition to optical devices, many advances have taken place in the area of high-power, high-frequency power transis- tors for radio-frequency transmission applications, due to the high thermal conductivity, high melting point, low dielectric constant, and high breakdown voltage of III-nitrides. At the same time, III-nitride alloys differ from the rest of III-V compound semiconductors in many aspects. Their most thermodynamically stable structure is wurtzite; they exhibit strong piezoelectric fields; they are chemically and physically strong, etc. In addition to these inherent properties, there are many technical challenges associated with the growth and processing of these materials. Most specifically, lack of commercially available native substrates has forced the researchers to use substrates with mismatched lattice constants and different thermal expansion coefficients. New ideas have had to be developed in order to reduce the number of dislocations present in the resulting material grown atop these substrates. Doping problems also, especially p-type doping, has plagued the development of these materials for a long time.
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Highly Nonlinear and Near-Zero Ultra-Flattened Dispersion Dodecagonal Photonic Crystal Fibers

Highly Nonlinear and Near-Zero Ultra-Flattened Dispersion Dodecagonal Photonic Crystal Fibers

Photonic crystal fibers (PCFs) have claddings that contain a central defect region surrounded by multiple air holes running along the fiber length. They have been one of the most interesting developments in recent fiber optics. The dispersion, confinement loss, and nonlinearity can be easily controlled by varying the structural parameters of the PCF such as the size of the air holes and their number and position [1– 4]. Controlling dispersion and achieving high nonlinearity along with low confinement loss is very crucial in PCFs. Highly nonlinear PCFs (HN-PCF) are suitable for a variety of novel applications including wavelength conversion [5], optical parametric amplification and supercontinum generation [6–8]. Also, they are attractive candidates for application in future high capacity, in all optical networks.
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Scalable Methods for Deterministic Integration of Quantum
Emitters in Photonic Crystal Cavities

Scalable Methods for Deterministic Integration of Quantum Emitters in Photonic Crystal Cavities

a career’s worth of advice into a summer’s worth of collaboration; to Se-Heon, Uday and Mike for many insightful tips and conversations; to Jingqing, whose perspective — whether about science, food or fun — was extraordinarily sharp, amusingly playful, and always appreciated; to Max, who openly shared a refreshing (often amusing) perspective on everything, expressed the most admirable humility I have ever known (“mistakes were made. . . ”), exhibited boundless resilience when faced with a challenge, and who was as successful at getting you to think deeply about a problem as anyone could be (“No, that can’t be right, Max” “How can I explain this to him,” “There certainly isn’t going to be any magic”); to Pawel and Claudia, two of the most focused and brilliant students I have ever met, who set the bar way too high and then somehow blow away all expectations; and to Akram, Ben, Chris, Dvin, Erika, Guangxi, Jeebs, Jeff, Joyce, Mladen, William, Xio, Zhenyu, and the many other amazing people I’ve had the pleasure of interacting with over my time in the group. To Kate, who kept us all happy, healthy and generally in one piece (Aditya may no longer own a pocket knife), I thank you for everything you did organizing us, corralling us, feeding us, reorganizing us, and generally putting up with anything and everything we threw your way. I greatly enjoyed our many conversations whether about science, acting, life or girl scout cookies, and admire your drive, enthusiasm and curiosity.
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PMD Tolerance of CSRZ-DPSK and -DQPSK Systems in 40 Gb/s DWDM Systems in Presence of Nonlinearities

PMD Tolerance of CSRZ-DPSK and -DQPSK Systems in 40 Gb/s DWDM Systems in Presence of Nonlinearities

Fig. 3 shows the contour map and Q-surface of single channel CSRZ DPSK system. As shown in Fig. 3(a), the vertical axis represents nonlinear coefficient and horizontal axis represents the PMD coefficient. At low nonlinear coefficient, when PMD coefficient (x) is increased Q-value decreases. When x is increased beyond 3.5, the Q-value goes below the acceptable level. With increased nonlinearity, the Q-value decreases with low PMD coefficient. But the Q-value does not remain linear, rather increased nonlinear coefficient reduces the effects of PMD. For example when x is increased from 3.3 to 4.5, the increased value of y from 1 to 4 gives the same Q- value. Same data is represented in 3-D form in Figure 3(b). It is clear from Fig. 3(b) that the Q-value changes rapidly.
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Reliability and Performance Evaluation of Fault-aware Routing Methods for Network-on-Chip Architectures (RESEARCH NOTE)

Reliability and Performance Evaluation of Fault-aware Routing Methods for Network-on-Chip Architectures (RESEARCH NOTE)

Nowadays, faults and failures are increasing especially in complex systems such as Network-on-Chip (NoC) based Systems-on-a-Chip (SoC) due to the increasing susceptibility and decreasing feature sizes. On the other hand, fault-tolerant routing algorithms have an evident effect on tolerating permanent faults and improving the reliability of a NoC based system. This paper presents reliability and performance evaluation of two main kinds of fault-aware routing algorithms, deterministic and adaptive, used in NoC architectures. The investigated methods have a multi-level structure for fault- tolerance and therefore, each level can be separately evaluated. To demonstrate the effectiveness of these methods, we propose an analytical approach for reliability assessment based on combinatorial reliability models to show the effect of fault-aware routing algorithms on overall NoC reliability. However, for performance evaluation, we conduct extensive simulations on different applications.
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