[Show abstract][Hide abstract] ABSTRACT: Compact 48 × 48 and 23 × 23 arrayed waveguide grating (AWG) devices are realized by using SU-8 strip waveguides fabricated with the process of direct ultraviolet (UV) photolithography. The demonstrated 48-channel and 23-channel AWG devices operating around 1550 nm have a channel spacing of 0.8 nm (100 GHz) and 3.2 nm (400 GHz), respectively. Due to the high index-contrast of the SU-8 strip waveguide, the fabricated AWG has a very compact size of only about 0.22 × 0.47 cm<sup>2</sup>. For the fabricated 100 GHz-spaced AWG, the crosstalk between adjacent channels is less than -15 dB, and the polarization-dependent wavelength is about 0.72 nm (@1543.5 nm). The fabricated 400 GHz-spaced AWG device exhibits a crosstalk of less than -20 dB, a polarization-dependent wavelength of 0.02 nm (@1559.6 nm). Finally the temperature tenability of the present AWG device is also characterized. A 12 nm tuning range is observed as the temperature changes from 25°C to 115°C.
Full-text · Article · Aug 2011 · Journal of Lightwave Technology
[Show abstract][Hide abstract] ABSTRACT: BOOM is a photonic integration concept that aims to develop compact, cost-effective and power efficient silicon photonic components for high capacity routing functionalities. To accomplish this, flip-chip bonding and heterogeneous wafer scale fabrication techniques are employed that enable Si manufacturing with III-IV material processing. We present in this paper the second generation of BOOM devices that perform all-optical wavelength conversion, label processing and switching on SOI nano-wire boards.
[Show abstract][Hide abstract] ABSTRACT: We present 160Gb/s all-optical wavelength conversion using an SOA and a 3rd order racetrack resonator integrated on a SOI nanowire platform. The scheme requires 0.5W of electrical power and the power penalty is <;3 dB.
[Show abstract][Hide abstract] ABSTRACT: During the past years, monolithic integration in InP has been the driving force for the realization of integrated photonic routing systems. The advent of silicon as a basis for cost-effective integration and its potential blend with III-V material is now opening exciting opportunities for the development of new, high-performance switching and routing equipment. Following this rationale, BOOM-as a European research initiative-aims to develop compact, cost-effective, and power-efficient silicon photonic components to enable optical Tb/s routers for current and new generation broadband core networks. This “siliconization” of photonic routers is expected to enable ultrahigh bit rates as well as higher levels of integration and power efficiency. The BOOM “device portfolio” includes all-optical wavelength converters, ultradense wave-division multiplexing (UDWDM) photodetectors, and high-speed transmitters; all based on silicon waveguide substrates. Here, we present the device concepts, the fabrication of photonic building blocks and the experiments carried out as the initial steps toward the realization of the first high-capacity silicon photonic router.
Full-text · Article · Nov 2010 · IEEE Journal of Selected Topics in Quantum Electronics
[Show abstract][Hide abstract] ABSTRACT: The European BOOM project aims at the realization of high-capacity photonic routers using the silicon material as the base for functional and cost-effective integration. Here we present the design, fabrication and testing of the first BOOMgeneration of hybrid integrated silicon photonic devices that implement key photonic routing functionalities. Ultra-fast all-optical wavelength converters and micro-ring resonator UDWDM label photodetectors are realized using either 4um SOI rib or SOI nanowire boards. For the realization of these devices, flip-chip compatible non-linear SOAs and evanescent PIN detectors have been designed and fabricated. These active components are integrated on the SOI boards using high precision flip-chip mounting and heterogeneous InP-to-silicon integration techniques. This type of scalable and cost-effective silicon-based component fabrication opens up the possibility for the realization of chip-scale, power efficient, Tb/s capacity photonic routers.
[Show abstract][Hide abstract] ABSTRACT: We report a new family of ultra-fast all-optical wavelength converters. The device architecture employs a single SOA and filtering elements integrated in silicon-on-insulator substrates. These schemes enable high-integration density and low power consumption.
[Show abstract][Hide abstract] ABSTRACT: Deeply-etched SiO<sub>2</sub> optical ridge waveguides are fabricated and characterized. A detailed discussion of the fabrication process (especially for the deep etching process) is presented. The measured propagation losses for the fabricated waveguides with different core widths range from 0.33 ~ 0.81 dB/mm. The loss is mainly caused by the scattering due to the sidewall roughness. The losses in bending sections are also characterized, which show the possibility of realizing a small bending radius (several tens of microns). 1 Ã N (N = 2, 4, 8) multimode interference couplers based on the deeply-etched SiO<sub>2</sub> ridge waveguide are also fabricated and show fairly good performances.
No preview · Article · Feb 2010 · IEEE Journal of Quantum Electronics
[Show abstract][Hide abstract] ABSTRACT: InGaAs PIN photodetectors heterogeneously integrated on silicon-on-insulator waveguides are fabricated and characterized. Efficient evanescent coupling between silicon-on-insulator waveguides and InGaAs photodetectors is achieved. The fabricated photodetectors can work well without external bias and have a very low dark current of 10pA. The measured responsivity of a 40microm-long photodetector is 1.1A/W (excluding the coupling loss between the fiber and the SOI waveguide) at a wavelength of 1550nm and shows good linearity for an input power range of 40dB. Due to the large absorption coefficient of InGaAs and the efficient evanescent coupling, the fabricated photodetectors can cover the whole S, C and L communication bands.
[Show abstract][Hide abstract] ABSTRACT: Small suspended SU-8 optical waveguides with a high refractive index contrast are designed and optimized. The single-mode condition and the bending characteristics of the present waveguide are numerically calculated by using a full-vectorial finite-difference method. Pure bending losses and transition losses of bending waveguides with different bending radii and different core widths are studied. The simulation results show that a wider core is helpful to reduce the pure bending loss. For example, when the core width is chosen as 2 µm, a very small bending radius (∼5 µm) can be achieved. However the transition loss is high. When a small total bending loss (≪0.1dB/90° bend) is required, the minimal bending radius is about 7 µm when an optimal offset is introduced. A crossing structure with two arms to support the suspended waveguides is designed and optimized by using a two-dimensional finite-difference time-domain method. The structure parameters (e.g., the expanding width, the taper length and the length of the insert straight section) of the crossing structure are optimized to minimize the excess loss. The optimal crossing structures exhibits a low excess loss (≪0.1 dB) and performs well in a wide wavelength range (1500 nm∼1600 nm).
[Show abstract][Hide abstract] ABSTRACT: The design of small suspended SU-8 optical waveguides is presented. A very small bending radius (~5μm) can be achieved because of the high-index contrast. A crossing structure is designed and optimized with low loss (<0.1dB) as the arms to support the suspended waveguides.
[Show abstract][Hide abstract] ABSTRACT: Compact microring resonator devices are realized by using a small SU-8 polymer strip waveguide that has an SU-8 polymer core (n ~ 1.573), an SiO2 buffer (n ~ 1.445), and an air cladding. Due to the high index contrast of the optical waveguide, a small bending radius ( ~ 150 mum) is used for the MRR. To enhance the coupling between the access optical waveguides and the microring, 2 times 2 multimode interference couplers are used. The measured spectral response of the through port shows a high extinction ratio of over 15 dB and a 3-dB bandwidth of about 0.38 nm (corresponding to a moderate Q-value of ~ 4500).
Full-text · Article · Nov 2009 · Journal of Lightwave Technology
[Show abstract][Hide abstract] ABSTRACT: Ultrasharp silicon-on-insulator (SOI) nanowire bends (with a bending radius of R < 2 mu m) are analyzed numerically. It is shown that the calculated bending losses for ultrasharp bends are overestimated when using a modal analysis method based on finite-difference method. In this case, reliable estimation of the bending loss can be made with a 3-D finite-difference time-domain (3-D-FDTD) method. By using 3-D-FDTD simulation, the losses in SOI nanowire bends with different structures and parameters are studied. By increasing the core width or height of the waveguide, one can reduce the bending loss at longer wavelengths for TE mode while the bending performance at shorter wavelengths degrades due to the multimode effect. Increasing the core height is much more effective to reduce the bending loss of TM mode than increasing core width. The relationship between the intrinsic Q -factor of a microring resonator and the bending radius is also obtained.
No preview · Article · Nov 2009 · IEEE Journal of Selected Topics in Quantum Electronics
[Show abstract][Hide abstract] ABSTRACT: We design and demonstrate the first higher-order silicon micro-ring resonators suitable for wavelength conversion. We show that 40 and 160 Gb/s wavelength conversion is feasible with a SOA followed by 2<sup>nd</sup> and 3<sup>rd</sup> order MRRs respectively.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate design, fabrication and measurement of silicon-on-insulator microring resonators suitable for ultra dense WDM applications with a channel spacing of 0.1 nm. Considerations about applying it to practical use are also discussed.
[Show abstract][Hide abstract] ABSTRACT: Small SU-8 ridge optical waveguides with an air cladding and a SiO<sub>2</sub> buffer on Si substrate have been realized by using a direct ultraviolet (UV) photolithography technology. The propagation loss measured by the cut-back method is about 0.1 dB/mm (@1550 nm) when the core width is 2.8 ??m. The bending losses of the present SU-8 optical ridge waveguides are also characterized. The measured results show that the bending loss decreases exponentially as the bending radius increases and the total loss can be reduced effectively by introducing an appropriate offset between two connected sections with different curvatures. A small bending radius (as small as 75 ??m) is still allowed for the requirement of a small bending loss (< 0.1 dB) when an offset of 0.1 ??m is introduced. Finally, by using this kind of waveguide, a small 1 ?? 2 Y-branch power splitter is fabricated and characterized.
Full-text · Article · Oct 2009 · Journal of Lightwave Technology
[Show abstract][Hide abstract] ABSTRACT: Integrating III-V materials on Si is a promising candidate to realize both passive and active optical functions on a single silicon chip. We have developed this heterogeneous integration technology by means of an adhesive die-to-wafer bonding process under a low temperature. In this paper, efficient evanescent coupling between SOI waveguides and heterogeneously-integrated III-V pin photodetectors is proposed. The serious absorption by p-InGaAs and metal contact layers are greatly reduced by introducing a central opening on these layers. The thickness of the i-InGaAs layer is also optimized towards efficient absorption.
[Show abstract][Hide abstract] ABSTRACT: Compact microracetrack resonator (MRR) devices are presented with small SU-8 polymer strip waveguides. The SU-8 strip waveguide has an SU-8 polymer core (n~1.573) , a SiO<sub>2</sub> buffer (n~1.445), and an air cladding. The fabricated straight waveguide has a low propagation loss of about 0.1 dB/mm. With such a high index-contrast optical waveguide, a compact MRR with a small bending radius (~150 mum) are designed and fabricated. The measured spectral responses of the through/drop ports show a Q-factor of 8000.
No preview · Article · Mar 2009 · IEEE Photonics Technology Letters
[Show abstract][Hide abstract] ABSTRACT: The characteristics of tapered lens fibers (TLFs) are analyzed by using a finite-difference time-domain (FDTD) method. Two types of TLFs are considered, namely, a tapered-cladding TLF and a tapered-core TLF. The radial FDTD method is first used to simulate light focusing for these two types of TLFs. It is shown that the tapered-core TLF has a smaller focus spot size and a larger transmission loss than the tapered-cladding TLF. The butt-coupling between a TLF of either type and a Si rib waveguide is then simulated by a three-dimensional FDTD method. The tapered-core TLF has a smaller coupling loss to the Si rib waveguide but a similar total loss (the sum of the coupling loss and the transmission loss), as compared with the tapered-cladding TLF.
[Show abstract][Hide abstract] ABSTRACT: A 2×2 tapered multimode interference (MMI) coupler is designed and fabricated by using air-cladded SU-8 rectangular waveguide, which is effective in reducing the device size and improving the self-imaging quality. The parabolically tapered MMI section is used to reduce further the size of the MMI coupler. A compact 2×2 coupler with a total MMI size of about 5.3×34.2 μ m <sup>2</sup> is demonstrated and characterized. The measurement results show that the fabricated 2×2 MMI coupler has relatively small excess loss and nonuniformity for both polarizations in a broad wavelength range (from 1480 to 1630 nm ).
Full-text · Article · Dec 2008 · Applied Physics Letters