Polarization management for silicon photonic integrated circuits
TL;DR: Polarization management is very important for photonic integrated circuits (PICs) and their applications as mentioned in this paper, however, due to geometrical anisotropy and fabrication inaccuracies, the characteristics of the guided transverseelectrical (TE) and transverse-magnetic (TM) modes are generally different.
Abstract: Polarization management is very important for photonic integrated circuits (PICs) and their applications. Due to geometrical anisotropy and fabrication inaccuracies, the characteristics of the guided transverse-electrical (TE) and transverse-magnetic (TM) modes are generally different. Polarization-dependent dispersion and polarization-dependent loss are such manifestations in PICs. These issues become more severe in high index contrast structures such as nanophotonic waveguides made of silicon-on-insulator (SOI), which has been regarded as a good platform for optical interconnects because of the compatibility with CMOS processing. Recently, polarization division multiplexing (PDM) with coherent detection using silicon photonics has also attracted much attention. This trend further highlights the importance of polarization management in silicon PICs. The authors review their work on polarization management for silicon PICs using the polarization independence and polarization diversity methods. Polarization issues and solutions in PICs made of SOI nanowires and ridge waveguides are discussed.
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TL;DR: In this paper, the authors focus on the discussion of silicon-based (de) multiplexers, including WDM filters, PDM devices, and SDM devices to achieve Peta-bit optical interconnects.
Abstract: Abstract An effective solution to enhance the capacity of an optical-interconnect link is utilizing advanced multiplexing technologies, like wavelength-division-multiplexing (WDM), polarization-division multiplexing (PDM), spatial-division multiplexing (SDM), bi-directional multiplexing, etc. On-chip (de)multiplexers are necessary as key components for realizing these multiplexing systems and they are desired to have small footprints due to the limited physical space for on-chip optical interconnects. As silicon photonics has provided a very attractive platform to build ultrasmall photonic integrated devices with CMOS-compatible processes, in this paper we focus on the discussion of silicon-based (de)multiplexers, including WDM filters, PDM devices, and SDM devices. The demand of devices to realize a hybrid multiplexing technology (combining WDM, PDM and SDM) as well as a bidirectional multiplexing technologies are also discussed to achieve Peta-bit optical interconnects.
242 citations
Cites background from "Polarization management for silicon..."
...A silicon hybrid plasmonic waveguide consisting of a SOI nanowire, a metal cap and an ultra-thin SiO2 layer (hd) between them (see Figure 20A [137]) can also be used to realize an asymmetrical coupling system for PBSs....
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...Furthermore, it is also desired to achieve broadband PBSs and PRs, which make it possible to work together with the WDM technology to form a kind of hybrid multiplexing system....
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...Among them, a DC structure is an attractive option for PBSs because of its structural simplicity....
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...In contrast, asymmetrical coupling systems have been considered as an improved option to achieve ultra-short and ultra-broadband PBSs [102], for which the waveguides are optimized to satisfy the phase-matching condition for only one polarization so that complete cross-coupling occurs....
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...It has been realized that most photonic integrated devices are polarization dependent due to the birefringence of optical waveguides (as summarized in Table 2), which provides various ways to realize waveguide-type PBSs, including multimode interferometers (MMIs) [106–110], DCs [111–118], MZIs [119–121], photonic crystal (PhC) structures [122–126], AWGs [127], MRRs [128], etc....
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TL;DR: In this paper, the advantages and challenges associated with these two material platforms are discussed, and the case of dispersive spectrometers, which are widely used in various silicon photonic applications, is presented.
Abstract: The high index contrast silicon-on-insulator platform is the dominant CMOS compatible platform for photonic integration. The successful use of silicon photonic chips in optical communication applications has now paved the way for new areas where photonic chips can be applied. It is already emerging as a competing technology for sensing and spectroscopic applications. This increasing range of applications for silicon photonics instigates an interest in exploring new materials, as silicon-on-insulator has some drawbacks for these emerging applications, e.g., silicon is not transparent in the visible wavelength range. Silicon nitride is an alternate material platform. It has moderately high index contrast, and like silicon-on-insulator, it uses CMOS processes to manufacture photonic integrated circuits. In this paper, the advantages and challenges associated with these two material platforms are discussed. The case of dispersive spectrometers, which are widely used in various silicon photonic applications, is presented for these two material platforms.
234 citations
Cites background from "Polarization management for silicon..."
...components such as waveguides, splitters, wavelength filters, interferometers, resonators, polarization management devices and couplers to guide light in and out of the silicon chip [22], [27]–[29]....
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TL;DR: In this article, a review of the recent progresses of multimode silicon photonic devices and circuits is given, including on-chip multichannel mode (de)multiplexers, multimode waveguide bends and crossings.
Abstract: Abstract Multimode silicon photonics is attracting more and more attention because the introduction of higher-order modes makes it possible to increase the channel number for data transmission in mode-division-multiplexed (MDM) systems as well as improve the flexibility of device designs. On the other hand, the design of multimode silicon photonic devices becomes very different compared with the traditional case with the fundamental mode only. Since not only the fundamental mode but also the higher-order modes are involved, one of the most important things for multimode silicon photonics is the realization of effective mode manipulation, which is not difficult, fortunately because the mode dispersion in multimode silicon optical waveguide is very strong. Great progresses have been achieved on multimode silicon photonics in the past years. In this paper, a review of the recent progresses of the representative multimode silicon photonic devices and circuits is given. The first part reviews multimode silicon photonics for MDM systems, including on-chip multichannel mode (de)multiplexers, multimode waveguide bends, multimode waveguide crossings, reconfigurable multimode silicon photonic integrated circuits, multimode chip-fiber couplers, etc. In the second part, we give a discussion about the higher-order mode-assisted silicon photonic devices, including on-chip polarization-handling devices with higher-order modes, add-drop optical filters based on multimode Bragg gratings, and some emerging applications.
179 citations
16 Aug 2018
TL;DR: This paper will concentrate on the key technological milestones that were crucial in demonstrating the capability of silicon photonics as both a successful technical platform, as well as indicating the potential for commercial success.
Abstract: In this paper, we present a brief history of silicon photonics from the early research papers in the late 1980s and early 1990s, to the potentially revolutionary technology that exists today. Given that other papers in this special issue give detailed reviews of key aspects of the technology, this paper will concentrate on the key technological milestones that were crucial in demonstrating the capability of silicon photonics as both a successful technical platform, as well as indicating the potential for commercial success. The paper encompasses discussion of the key technology areas of passive devices, modulators, detectors, light sources, and system integration. In so doing, the paper will also serve as an introduction to the other papers within this special issue.
162 citations
Cites background from "Polarization management for silicon..."
...It has allowed the implementation of passive components with outstanding performance including waveguides, splitters [70]–[72], interferometers [73], resonators [74], [75], (de)multiplexers [76], polarization management devices [77], grating couplers [78]–[92], etc....
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TL;DR: An ultracompact and low-loss TM-pass polarizer on silicon is proposed and demonstrated experimentally with a subwavelength-grating (SWG) waveguide to support Bloch mode for TM polarization.
Abstract: An ultracompact and low-loss TM-pass polarizer on silicon is proposed and demonstrated experimentally with a subwavelength-grating (SWG) waveguide The SWG waveguide is designed to support Bloch mode for TM polarization so that the incident TM-polarized light goes through the SWG waveguide with very low excess loss On the other hand, for TE polarization, the SWG waveguide works as a Bragg reflector, and consequently the incident TE-polarized light is reflected For a fabricated ∼9 μm long polarizer (with the period number N=20), the measured extinction ratio is ∼27 dB and the excess loss is ∼05 dB at the central wavelength 1550 nm The bandwidth to achieve an extinction ratio of 20 dB is about 60 nm (from 1520 to 1580 nm) When increasing the period number to N=40, the measured extinction ratio is up to 40 dB (which is not as high as the expected theoretical value 65 dB due to the limit of the measurement system)
141 citations
References
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TL;DR: In this paper, the state-of-the-art CMOS silicon-on-insulator (SOI) foundries are now being utilized in a crucial test of 1.55mum monolithic optoelectronic (OE) integration, a test sponsored by the Defense Advanced Research Projects Agency (DARPA).
Abstract: The pace of the development of silicon photonics has quickened since 2004 due to investment by industry and government. Commercial state-of-the-art CMOS silicon-on-insulator (SOI) foundries are now being utilized in a crucial test of 1.55-mum monolithic optoelectronic (OE) integration, a test sponsored by the Defense Advanced Research Projects Agency (DARPA). The preliminary results indicate that the silicon photonics are truly CMOS compatible. RD however, lasing has not yet been attained. The new paradigm for the Si-based photonic and optoelectric integrated circuits is that these chip-scale networks, when suitably designed, will operate at a wavelength anywhere within the broad spectral range of 1.2-100 mum, with cryocooling needed in some cases
1,789 citations
TL;DR: It is shown that by use of a novel waveguide geometry the field can be confined in a 50-nm-wide low-index region with a normalized intensity of 20 microm(-2), approximately 20 times higher than what can be achieved in SiO2 with conventional rectangular waveguides.
Abstract: We present a novel waveguide geometry for enhancing and confining light in a nanometer-wide low-index material. Light enhancement and confinement is caused by large discontinuity of the electric field at highindex-contrast interfaces. We show that by use of such a structure the field can be confined in a 50-nm-wide low-index region with a normalized intensity of 20 mm 22 . This intensity is approximately 20 times higher than what can be achieved in SiO2 with conventional rectangular waveguides. © 2004 Optical Society of America OCIS codes: 030.4070, 130.0130, 130.2790, 230.7370, 230.7380, 230.7390, 230.7400. Recent results in integrated optics have shown the ability to guide, bend, split, and f ilter light on chips by use of optical devices based on high-index-contrast waveguides. 1–5 In all these devices the guiding mechanism is based on total internal ref lection (TIR) in a highindex material (core) surrounded by a low-indexmaterial (cladding); the TIR mechanism can strongly confine light in the high-index material. In recent years a number of structures have been proposed to guide or enhance light in low-index materials, 6–1 1 relying on external ref lections provided by interference effects. Unlike TIR, the external ref lection cannot be perfectly unity; therefore the modes in these structures are inherently leaky modes. In addition, since interference is involved, these structures are strongly wavelength dependent. Here we show that the optical field can be enhanced and conf ined in the low-index material even when light is guided by TIR. For a high-index-contrast interface, Maxwell’s equations state that, to satisfy the continuity of the normal component of electric f lux density D, the corresponding electric field (E-field) must undergo a large discontinuity with much higher amplitude in the low-index side. We show that this discontinuity can be used to strongly enhance and confine light in a nanometer-wide region of low-index material. The proposed structure presents an eigenmode, and it is compatible with highly integrated photonics technology. The principle of operation of the novel structure can be illustrated by analysis of the slab-based structure shown in Fig. 1(a), where a low-index slot is embedded between two high-index slabs (shaded regions). The novel structure is hereafter referred to as a slot waveguide. The slot waveguide eigenmode can be seen as being formed by the interaction between the fundamental eigenmodes of the individual slab waveguides. Rigorously, the analytical solution for the transverse E-field profile Ex of the fundamental TM eigenmode of the slab-based slot waveguide is
1,716 citations
TL;DR: In this paper, the authors review the most recent progress in this field, including low-threshold silicon Raman lasers with racetrack ring resonator cavities, the first germanium-on-silicon lasers operating at room temperature, and hybrid silicon microring and microdisk lasers.
Abstract: Silicon lasers have long been a goal for semiconductor scientists, and a number of important breakthroughs in the past decade have focused attention on silicon as a photonic platform. Here we review the most recent progress in this field, including low-threshold silicon Raman lasers with racetrack ring resonator cavities, the first germanium-on-silicon lasers operating at room temperature, and hybrid silicon microring and microdisk lasers. The fundamentals of carrier transition physics in crystalline silicon are discussed briefly. The basics of several important approaches for creating lasers on silicon are explained, and the challenges and opportunities associated with these approaches are discussed. Silicon lasers have long been a goal for semiconductor scientists. This Progress Article reviews the most recent developments in this field, including silicon Raman lasers, the first germanium-on-silicon lasers operating at room temperature, and hybrid silicon microring and microdisk lasers. Challenges and opportunities for the present approaches are also discussed.
1,045 citations
IBM1
TL;DR: The fabrication and accurate measurement of propagation and bending losses in single-mode silicon waveguides with submicron dimensions fabricated on silicon-on-insulator wafers with record low numbers can be used as a benchmark for further development of silicon microphotonic components and circuits.
Abstract: We report the fabrication and accurate measurement of propagation and bending losses in single-mode silicon waveguides with submicron dimensions fabricated on silicon-on-insulator wafers. Owing to the small sidewall surface roughness achieved by processing on a standard 200mm CMOS fabrication line, minimal propagation losses of 3.6+/-0.1dB/cm for the TE polarization were measured at the telecommunications wavelength of 1.5microm. Losses per 90 masculine bend are measured to be 0.086+/-0.005dB for a bending radius of 1microm and as low as 0.013+/-0.005dB for a bend radius of 2microm. These record low numbers can be used as a benchmark for further development of silicon microphotonic components and circuits.
999 citations
Journal Article•
809 citations
"Polarization management for silicon..." refers background in this paper
..., TM) by choosing different core widths (w1 and w2) for the two bent waveguides and consequently a complete crosscoupling occurs when choosing the length of the coupling region [109]....
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