Integrated Optical Ultra-Broadband Add-Drop Filter in Silicon-On-Insulator Platform
11 Mar 2018-pp 1-3
TL;DR: A sub-wavelength grating waveguide is designed and integrated in two arms of a 2 × 2 Mach-Zehnder interferometer in silicon-on-insulator which is capable of drop-ping(adding) ultra-broad wavelength bands centering at λ ∼1550nm with band-edge extinction exceeding 35-dB.
Abstract: A sub-wavelength grating waveguide is designed and integrated in two arms of a 2 × 2 Mach-Zehnder interferometer in silicon-on-insulator which is capable of drop-ping(adding) ultra-broad wavelength bands centering at λ ∼1550nm with band-edge extinction exceeding 35-dB.
Citations
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01 Sep 2020
TL;DR: In this article, a broadband integrated notch filter, using the silicon nitride (Si 3 N 4 ) platform, is presented, which achieves an extinction ratio (ER) of 60 dB and a full width at half maximum (FWHM) of 10 nm at the central wavelength (CW) 785 nm.
Abstract: A broadband integrated notch filter, using the silicon nitride (Si 3 N 4 ) platform, is presented. It achieves an extinction ratio (ER) of 60 dB and a full width at half maximum (FWHM) of 10 nm at the central wavelength (CW) 785 nm. The main filter components are Bragg gratings (BGs). For separating the occurring reflections from the input waveguide, two identical BGs are combined with a directional coupler (DC) acting as optical circulator. The 3-dB bandwidth of the passband (790 nm to 1200 nm) is more than 400 nm.
Cites background or methods from "Integrated Optical Ultra-Broadband ..."
...An already known principle of the filter ([3, 4]) is shown in Fig....
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...One approach is based on a Mach-Zehnder interferometer (MZI) configuration [3, 4]....
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References
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TL;DR: This demonstration could represent the beginning of an era of chip-scale electronic–photonic systems with the potential to transform computing system architectures, enabling more powerful computers, from network infrastructure to data centres and supercomputers.
Abstract: An electronic–photonic microprocessor chip manufactured using a conventional microelectronics foundry process is demonstrated; the chip contains 70 million transistors and 850 photonic components and directly uses light to communicate to other chips. The rapid transfer of data between chips in computer systems and data centres has become one of the bottlenecks in modern information processing. One way of increasing speeds is to use optical connections rather than electrical wires and the past decade has seen significant efforts to develop silicon-based nanophotonic approaches to integrate such links within silicon chips, but incompatibility between the manufacturing processes used in electronics and photonics has proved a hindrance. Now Chen Sun et al. describe a 'system on a chip' microprocessor that successfully integrates electronics and photonics yet is produced using standard microelectronic chip fabrication techniques. The resulting microprocessor combines 70 million transistors and 850 photonic components and can communicate optically with the outside world. This result promises a way forward for new fast, low-power computing systems architectures. Data transport across short electrical wires is limited by both bandwidth and power density, which creates a performance bottleneck for semiconductor microchips in modern computer systems—from mobile phones to large-scale data centres. These limitations can be overcome1,2,3 by using optical communications based on chip-scale electronic–photonic systems4,5,6,7 enabled by silicon-based nanophotonic devices8. However, combining electronics and photonics on the same chip has proved challenging, owing to microchip manufacturing conflicts between electronics and photonics. Consequently, current electronic–photonic chips9,10,11 are limited to niche manufacturing processes and include only a few optical devices alongside simple circuits. Here we report an electronic–photonic system on a single chip integrating over 70 million transistors and 850 photonic components that work together to provide logic, memory, and interconnect functions. This system is a realization of a microprocessor that uses on-chip photonic devices to directly communicate with other chips using light. To integrate electronics and photonics at the scale of a microprocessor chip, we adopt a ‘zero-change’ approach to the integration of photonics. Instead of developing a custom process to enable the fabrication of photonics12, which would complicate or eliminate the possibility of integration with state-of-the-art transistors at large scale and at high yield, we design optical devices using a standard microelectronics foundry process that is used for modern microprocessors13,14,15,16. This demonstration could represent the beginning of an era of chip-scale electronic–photonic systems with the potential to transform computing system architectures, enabling more powerful computers, from network infrastructure to data centres and supercomputers.
1,058 citations
TL;DR: In this article, the authors show that the wavelength-dependent performance of a directional coupler (DC) in silicon-on-insulator (SOI) platform can be greatly engineered by suitable design optimizations.
Abstract: It has been shown that the wavelength-dependent performance of a directional coupler (DC) in silicon-on-insulator (SOI) platform can be greatly engineered by suitable design optimizations. Semianalytical coupled mode theory is used to optimize a nearly wavelength-independent design of a DC in an SOI substrate with a device layer thickness of 220 nm, operating in TE-polarization ( $\lambda \sim$ 1550 nm). The transmission characteristics of fabricated DCs are found to be indeed wavelength independent over a bandwidth of ${\text{100 nm}}$ (1525 nm $\leq \lambda \leq$ 1625 nm), consistent with the theoretical predictions. The average excess loss of such directional couplers is evaluated as $\sim\text{0.8}$ dB and there are scopes for its further reduction. These DCs are then used further to demonstrate integrated optical building blocks like power splitters (2 $\times$ 2, 1 $\times$ 4), Mach–Zehnder interferometers (2 $\times$ 2), and all-pass microring resonators. Their performances are also found to be uniform within the wavelength range mentioned and, thus, making them suitable for integrated silicon photonics for broadband applications.
37 citations
"Integrated Optical Ultra-Broadband ..." refers methods in this paper
...The 3-dB power splitter is implemented using WIDC which offers uniform power splitting over a broad wavelength span of ∼ 100 nm [4]....
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TL;DR: In this article, the dispersion in transmission characteristics of a ring resonator designed with silicon-on-insulator waveguides in all-pass configuration can be enhanced significantly by increasing interaction length of the directional coupler.
Abstract: It is shown that the dispersion in transmission characteristics of a ring resonator designed with silicon-on-insulator waveguides in all-pass configuration can be enhanced significantly by increasing interaction length of the directional coupler. This in turn helps to single-out highly extinct resonance(s) at and around the critically coupled wavelength. Such a device is found to be useful for a wide range of refractive index sensing for the cladding materials/analytes ( ${\text{1.0}} ). As a proof of concept, the sensor devices were fabricated and characterization results are shown to be consistent with theoretical prediction. The fabricated devices have been also used successfully to determine unknown refractive index of a given analyte (Newport F-IMF-150) with an error limit of $\delta n \sim {\text{1.67}} \times {\text{10}}^{-2}$ RIU. Analyzing experimental results, it is shown that the limit of detection can be further reduced ( $\ll {\text{10}^{{-3}}}$ RIU), if the perimeter of the ring is increased without compromising the round-trip waveguide loss. The superiority of such a sensor device lies in its simpler design rule, easier operation, wider range, and nearly accurate detection mechanism.
29 citations
"Integrated Optical Ultra-Broadband ..." refers methods in this paper
...The access waveguides are terminated with grating couplers enabling wavelength dependent device characterizations using a fiber-optic probe station [5]....
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TL;DR: This paper proposes to introduce two identical Bragg gratings in the arms of a Mach-Zehnder interferometer built with multimode interference 2 x 2 couplers to provide a reflective filter without circulator to enable the fabrication of grating based narrowband reflective filters having sharp spectral responses, which represents a major improvement in the filtering capability of the silicon platform.
Abstract: Bragg gratings operating in reflection are versatile filters that are an important building block of photonic circuits but, so far, their use has been limited due to the absence of CMOS compatible integrated circulators. In this paper, we propose to introduce two identical Bragg gratings in the arms of a Mach-Zehnder interferometer built with multimode interference 2 x 2 couplers to provide a reflective filter without circulator. We show that this structure has unique properties that significantly reduce phase noise distortions, avoid the need for thermal phase tuning, and make it compatible with complex apodization functions implemented through superposition apodization. We experimentally demonstrate several Bragg grating filters with high quality reflection spectra. For example, we successfully fabricated a 4 nm dispersion-less square-shaped filter having a sidelobe suppression ratio better than 15 dB and an in-band phase response with a group delay standard deviation of 2.0 ps. This result will enable the fabrication of grating based narrowband reflective filters having sharp spectral responses, which represents a major improvement in the filtering capability of the silicon platform.
29 citations
TL;DR: In this article, an ultra-compact multimode interference (MMI)-based diplexer is proposed with the assistance of subwavelength grating (SWG), which can engineer the effective refractive index for the modes and tune the beat length.
Abstract: With the assistance of subwavelength grating (SWG), an ultra-compact multimode interference (MMI)-based diplexer is proposed. A certain number of SWG pitches are implemented in the middle of the MMI section, which can engineer the effective refractive index for the modes and, therefore, tune the beat length. With proper tailoring of the grating parameters, the beat lengths of the two wavelengths can be reduced as well as the device length, which has to match several odd or even times of beat lengths of both wavelengths. As a result, the proposed wavelength diplexer is $43.4~\mu \text{m}$ in length, which is only ~30% of its conventional counterpart. It also displays a wide 1-dB bandwidth of ~150 nm around the wavelength of 1310 and ~120 nm around the wavelength of 1550 nm. The insertion losses are less than 0.1 dB for the two operating wavelengths while the extinction ratios are both better than 20 dB.
23 citations
"Integrated Optical Ultra-Broadband ..." refers methods in this paper
...Very recently, an integrated optical wavelength diplexer device has been reported using sub-wavelength grating waveguide (SWG) [3]....
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