Silicon photonics is the study and application of photonic systems which use silicon as an optical medium. The silicon is usually patterned with sub-micrometre precision, into microphotonic components. These operate in the infrared, most commonly at the 1.55 micrometre wavelength used by most fiber optic telecommunication systems. The silicon typically lies on top of a layer of silica in what (by analogy with a similar construction in microelectronics) is known as silicon on insulator (SOI).
Silicon photonic devices can be made using existing semiconductor fabrication techniques, and because silicon is already used as the substrate for most integrated circuits, it is possible to create hybrid devices in which the optical and electronic components are integrated onto a single microchip. Consequently, silicon photonics is being actively researched by many electronics manufacturers including IBM and Intel, as well as by academic research groups, as a means for keeping on track with Moore's Law, by using optical interconnects to provide faster data transfer both between and within microchips.
The propagation of light through silicon devices is governed by a range of nonlinear optical phenomena including the Kerr effect, the Raman effect, two-photon absorption and interactions between photons and free charge carriers. The presence of nonlinearity is of fundamental importance, as it enables light to interact with light, thus permitting applications such as wavelength conversion and all-optical signal routing, in addition to the passive transmission of light.
Silicon waveguides are also of great academic interest, due to their unique guiding properties, they can be used for communications, interconnects, biosensors, and they offer the possibility to support exotic nonlinear optical phenomena such as soliton propagation.
- 1 Applications
- 2 Physical properties
- 3 Solitons
- 4 References
In a typical optical link, data is first transferred from the electrical to the optical domain using an electro-optic modulator or a directly-modulated laser. An electro-optic modulator can vary the intensity and/or the phase of the optical carrier. In silicon photonics, a common technique to achieve modulation is to vary the density of free charge carriers. Variations of electron and hole densities change the real and the imaginary part of the refractive index of silicon as described by the empirical equations of Soref and Bennett. Modulators can consist of both forward-biased PIN diodes, which generally generate large phase-shifts but suffer of lower speeds, as well as of reverse-biased PN junctions. A prototype optical interconnect with microring modulators integrated with germanium detectors has been demonstrated. Non-resonant modulators, such as Mach-Zehnder interferometers, have typical dimensions in the millimeter range and are usually used in telecom or datacom applications. Resonant devices, such as ring-resonators, can have dimensions of few tens of micrometers only, occupying therefore much smaller areas. In 2013, researchers demonstrated a resonant depletion modulator that can be fabricated using standard Silicon-on-Insulator Complementary Metal-Oxide-Semiconductor (SOI CMOS) manufacturing processes. A similar device has been demonstrated as well in bulk CMOS rather than in SOI.
On the receiver side, the optical signal is typically converted back to the electrical domain using a semiconductor photodetector. The semiconductor used for carrier generation has usually a band-gap smaller than the photon energy, and the most common choice is pure germanium. Most detectors utilize a PN junction for carrier extraction, however, detectors based on metal-semiconductor junctions (with germanium as the semiconductor) have been integrated into silicon waveguides as well. More recently, silicon-germanium avalanche photodiodes capable of operating at 40 Gbit/s have been fabricated. Complete transceivers have been commercialized in the form of active optical cables.
Optical communications are conveniently classified by the reach, or length, of their links. The majority of silicon photonic communications have so far been limited to telecom and datacom applications, where the reach is of several kilometers or several meters respectively.
Silicon photonics, however, is expected to play a significant role in computercom as well, where optical links have a reach in the centimeter to meter range. In fact, progress in computer technology (and the continuation of Moore's Law) is becoming increasingly dependent on faster data transfer between and within microchips. Optical interconnects may provide a way forward, and silicon photonics may prove particularly useful, once integrated on the standard silicon chips. In 2006 Former Intel senior vice president Pat Gelsinger stated that, "Today, optics is a niche technology. Tomorrow, it's the mainstream of every chip that we build."
The first microprocessor with optical input/output (I/O) was demonstrated in December 2015 using an approach known as "zero-change" CMOS photonics. This first demonstration was based on a 45 nm SOI node, and the bi-directional chip-to-chip link was operated at a rate of 2×2.5 Gbit/s. The total energy consumption of the link was calculated to be of 16 pJ/b and was dominated by the contribution of the off-chip laser.
Some researchers believe an on-chip laser source is required. Others think that it should remain off-chip because of thermal problems (the quantum efficiency decreases with temperature, and computer chips are generally hot) and because of CMOS-compatibility issues. One such device is the hybrid silicon laser, in which the silicon is bonded to a different semiconductor (such as indium phosphide) as the lasing medium. Another possibility is the all-silicon Raman laser, in which silicon is the lasing medium.
In 2012, IBM announced that it had achieved optical components at the 90 nanometer scale that can be manufactured using standard techniques and incorporated into conventional chips. In September 2013, Intel announced technology to transmit data at speeds of 100 gigabits per second along a cable approximately five millimeters in diameter for connecting servers inside data centers. Conventional PCI-E data cables carry data at up to eight gigabits per second, while networking cables reach 40 Gbit/s. The latest version of the USB standard tops out at ten Gbit/s. The technology does not directly replace existing cables in that it requires a separate circuit board to interconvert electrical and optical signals. Its advanced speed offers the potential of reducing the number of cables that connect blades on a rack and even of separating processor, storage and memory into separate blades to allow more efficient cooling and dynamic configuration.
Graphene photodetectors have the potential to surpass germanium devices in several important aspects, although they remain about one order of magnitude behind current generation capacity, despite rapid improvement. Graphene devices can work at very high frequencies, and could in principle reach higher bandwidths. Graphene can absorb a broader range of wavelengths than germanium. That property could be exploited to transmit more data streams simultaneously in the same beam of light. Unlike germanium detectors, graphene photodetectors do not require applied voltage, which could reduce energy needs. Finally, graphene detectors in principle permit a simpler and less expensive on-chip integration. However, graphene does not strongly absorb light. Pairing a silicon waveguide with a graphene sheet better routes light and maximizes interaction. The first such device was demonstrated in 2011. Manufacturing such devices using conventional manufacturing techniques has not been demonstrated.
Optical routers and signal processors
Another application of silicon photonics is in signal routers for optical communication. Construction can be greatly simplified by fabricating the optical and electronic parts on the same chip, rather than having them spread across multiple components. A wider aim is all-optical signal processing, whereby tasks which are conventionally performed by manipulating signals in electronic form are done directly in optical form. An important example is all-optical switching, whereby the routing of optical signals is directly controlled by other optical signals. Another example is all-optical wavelength conversion.
Long range telecommunications using silicon photonics
Silicon microphotonics can potentially increase the Internet's bandwidth capacity by providing micro-scale, ultra low power devices. Furthermore, the power consumption of datacenters may be significantly reduced if this is successfully achieved. Researchers at Sandia, Kotura, NTT, Fujitsu and various academic institutes have been attempting to prove this functionality. A 2010 paper reported on a prototype 80 km, 12.5 Gbit/s transmission using microring silicon devices.
Optical guiding and dispersion tailoring
Silicon is transparent to infrared light with wavelengths above about 1.1 micrometres. Silicon also has a very high refractive index, of about 3.5. The tight optical confinement provided by this high index allows for microscopic optical waveguides, which may have cross-sectional dimensions of only a few hundred nanometers. Single mode propagation can be achieved, thus (like single-mode optical fiber) eliminating the problem of modal dispersion.
The strong dielectric boundary effects that result from this tight confinement substantially alter the optical dispersion relation. By selecting the waveguide geometry, it is possible to tailor the dispersion to have desired properties, which is of crucial importance to applications requiring ultrashort pulses. In particular, the group velocity dispersion (that is, the extent to which group velocity varies with wavelength) can be closely controlled. In bulk silicon at 1.55 micrometres, the group velocity dispersion (GVD) is normal in that pulses with longer wavelengths travel with higher group velocity than those with shorter wavelength. By selecting a suitable waveguide geometry, however, it is possible to reverse this, and achieve anomalous GVD, in which pulses with shorter wavelengths travel faster. Anomalous dispersion is significant, as it is a prerequisite for soliton propagation, and modulational instability.
In order for the silicon photonic components to remain optically independent from the bulk silicon of the wafer on which they are fabricated, it is necessary to have a layer of intervening material. This is usually silica, which has a much lower refractive index (of about 1.44 in the wavelength region of interest), and thus light at the silicon-silica interface will (like light at the silicon-air interface) undergo total internal reflection, and remain in the silicon. This construct is known as silicon on insulator. It is named after the technology of silicon on insulator in electronics, whereby components are built upon a layer of insulator in order to reduce parasitic capacitance and so improve performance.
Silicon has a focusing Kerr nonlinearity, in that the refractive index increases with optical intensity. This effect is not especially strong in bulk silicon, but it can be greatly enhanced by using a silicon waveguide to concentrate light into a very small cross-sectional area. This allows nonlinear optical effects to be seen at low powers. The nonlinearity can be enhanced further by using a slot waveguide, in which the high refractive index of the silicon is used to confine light into a central region filled with a strongly nonlinear polymer.
Kerr nonlinearity underlies a wide variety of optical phenomena. One example is four wave mixing, which has been applied in silicon to realise optical parametric amplification, parametric wavelength conversion, and frequency comb generation.,
Kerr nonlinearity can also cause modulational instability, in which it reinforces deviations from an optical waveform, leading to the generation of spectral-sidebands and the eventual breakup of the waveform into a train of pulses. Another example (as described below) is soliton propagation.
Silicon exhibits two-photon absorption (TPA), in which a pair of photons can act to excite an electron-hole pair. This process is related to the Kerr effect, and by analogy with complex refractive index, can be thought of as the imaginary-part of a complex Kerr nonlinearity. At the 1.55 micrometre telecommunication wavelength, this imaginary part is approximately 10% of the real part.
The influence of TPA is highly disruptive, as it both wastes light, and generates unwanted heat. It can be mitigated, however, either by switching to longer wavelengths (at which the TPA to Kerr ratio drops), or by using slot waveguides (in which the internal nonlinear material has a lower TPA to Kerr ratio). Alternatively, the energy lost through TPA can be partially recovered (as is described below) by extracting it from the generated charge carriers.
Free charge carrier interactions
The free charge carriers within silicon can both absorb photons and change its refractive index. This is particularly significant at high intensities and for long durations, due to the carrier concentration being built up by TPA. The influence of free charge carriers is often (but not always) unwanted, and various means have been proposed to remove them. One such scheme is to implant the silicon with helium in order to enhance carrier recombination. A suitable choice of geometry can also be used to reduce the carrier lifetime. Rib waveguides (in which the waveguides consist of thicker regions in a wider layer of silicon) enhance both the carrier recombination at the silica-silicon interface and the diffusion of carriers from the waveguide core.
A more advanced scheme for carrier removal is to integrate the waveguide into the intrinsic region of a PIN diode, which is reverse biased so that the carriers are attracted away from the waveguide core. A more sophisticated scheme still, is to use the diode as part of a circuit in which voltage and current are out of phase, thus allowing power to be extracted from the waveguide. The source of this power is the light lost to two photon absorption, and so by recovering some of it, the net loss (and the rate at which heat is generated) can be reduced.
Second-order nonlinearities cannot exist in bulk silicon because of the centrosymmetry of its crystalline structure. By applying strain however, the inversion symmetry of silicon can be broken. This can be obtained for example by depositing a silicon nitride layer on a thin silicon film. Second-order nonlinear phenomena can be exploited for optical modulation, spontaneous parametric down-conversion, parametric amplification, ultra-fast optical signal processing and mid-infrared generation. Efficient nonlinear conversion however requires phase matching between the optical waves involved. Second-order nonlinear waveguides based on strained silicon can achieve phase matching by dispersion-engineering. So far, however, experimental demonstrations are based only on designs which are not phase matched. It has been shown that phase matching can be obtained as well in silicon double slot waveguides coated with a highly nonlinear organic cladding and in periodically strained silicon waveguides.
The Raman effect
Silicon exhibits the Raman effect, in which a photon is exchanged for a photon with a slightly different energy, corresponding to an excitation or a relaxation of the material. Silicon's Raman transition is dominated by a single, very narrow frequency peak, which is problematic for broadband phenomena such as Raman amplification, but is beneficial for narrowband devices such as Raman lasers. Early studies of Raman amplification and Raman lasers started at UCLA which led to demonstration of net gain Silicon Raman amplifiers and silicon pulsed Raman laser with fiber resonator (Optics express 2004). Consequently, all-silicon Raman lasers have been fabricated in 2005.
The Brillouin effect
In the Raman effect, photons are red- or blue-shifted by optical phonons with a frequency of about 15 THz. However, silicon waveguides also support acoustic phonon excitations. Their interaction with light is called Brillouin scattering. The frequencies and mode shapes of these acoustic phonons are dependent on the geometry and size of the silicon waveguides. Therefore, the frequencies are tailorable from a few MHz to tens of GHz. Their interaction with light can among others be used to make narrowband optical amplifiers. The interaction between photons and acoustic phonons is also studied in the field of cavity optomechanics, although 3D optical cavities are not necessary to observe the interaction. For instance, besides in silicon waveguides the optomechanical coupling has also been demonstrated in fibers and in chalcogenide waveguides.
The evolution of light through silicon waveguides can be approximated with a cubic Nonlinear Schrödinger equation, which is notable for admitting sech-like soliton solutions. These optical solitons (which are also known in optical fiber) result from a balance between self phase modulation (which causes the leading edge of the pulse to be redshifted and the trailing edge blueshifted) and anomalous group velocity dispersion. Such solitons have been observed in silicon waveguides, by groups at the universities of Columbia, Rochester, and Bath.
- Soref, Richard A.; Lorenzo, Joseph P. (1986). "All-silicon active and passive guided-wave components for lambda= 1.3 and 1.6 microns". IEEE Journal of Quantum Electronics. 22: 873–879. Bibcode:1986IJQE...22..873S. doi:10.1109/JQE.1986.1073057.
- Jalali, Bahram; Fathpour, Sasan (2006). "Silicon photonics". Journal of Lightwave Technology. 24 (12): 4600–4615. Bibcode:2006JLwT...24.4600J. doi:10.1109/JLT.2006.885782.
- Almeida, V. R.; Barrios, C. A.; Panepucci, R. R.; Lipson, M (2004). "All-optical control of light on a silicon chip". Nature. 431 (7012): 1081–1084. Bibcode:2004Natur.431.1081A. doi:10.1038/nature02921. PMID 15510144.
- Silicon photonics. Springer. 2004. ISBN 3-540-21022-9.
- Silicon photonics: an introduction. John Wiley and Sons. 2004. ISBN 0-470-87034-6.
- Lipson, Michal (2005). "Guiding, Modulating, and Emitting Light on Silicon – Challenges and Opportunities". Journal of Lightwave Technology. 23 (12): 4222–4238. Bibcode:2005JLwT...23.4222L. doi:10.1109/JLT.2005.858225.
- "Silicon Integrated Nanophotonics". IBM Research. Retrieved 14 July 2009.
- "Silicon Photonics". Intel. Retrieved 14 July 2009.
- SPIE (5 March 2015). "Yurii A. Vlasov plenary presentation: Silicon Integrated Nanophotonics: From Fundamental Science to Manufacturable Technology". SPIE Newsroom. doi:10.1117/2.3201503.15.
- Dekker, R; Usechak, N; Först, M; Driessen, A (2008). "Ultrafast nonlinear all-optical processes in silicon-on-insulator waveguides". Journal of Physics D. 40 (14): R249–R271. Bibcode:2007JPhD...40..249D. doi:10.1088/0022-3727/40/14/r01.
- Butcher, Paul N.; Cotter, David (1991). The elements of nonlinear optics. Cambridge University Press. ISBN 0-521-42424-0.
- Hsieh, I.-Wei; Chen, Xiaogang; Dadap, Jerry I.; Panoiu, Nicolae C.; Osgood, Richard M.; McNab, Sharee J.; Vlasov, Yurii A. (2006). "Ultrafast-pulse self-phase modulation and third-order dispersion in Si photonic wire-waveguides". Optics Express. 14 (25): 12380–12387. Bibcode:2006OExpr..1412380H. doi:10.1364/OE.14.012380.
- Zhang, Jidong; Lin, Qiang; Piredda, Giovanni; Boyd, Robert W.; Agrawal, Govind P.; Fauchet, Philippe M. (2007). "Optical solitons in a silicon waveguide". Optics Express. 15 (12): 7682–7688. Bibcode:2007OExpr..15.7682Z. doi:10.1364/OE.15.007682.
- Ding, W.; Benton, C.; Gorbach, A. V.; Wadsworth, W. J.; Knight, J. C.; Skryabin, D. V.; Gnan, M.; Sorrel, M.; de la Rue, R. M. (2008). "Solitons and spectral broadening in long silicon-on- insulator photonic wires". Optics Express. 16 (5): 3310–3319. Bibcode:2008OExpr..16.3310D. doi:10.1364/OE.16.003310.
- Soref, Richard A.; Bennett, Brian R. (1987). "Electrooptical effects in silicon". IEEE Journal of Quantum Electronics. 23 (1): 123–129. Bibcode:1987IJQE...23..123S. doi:10.1109/JQE.1987.1073206.
- Barrios, C.A.; Almeida, V.R.; Panepucci, R.; Lipson, M. (2003). "Electrooptic Modulation of Silicon-on-Insulator Submicrometer-Size Waveguide Devices". Journal of Lightwave Technology. 21 (10): 2332–2339. Bibcode:2003JLwT...21.2332B. doi:10.1109/JLT.2003.818167.
- Liu, Ansheng; Liao, Ling; Rubin, Doron; Nguyen, Hat; Ciftcioglu, Berkehan; Chetrit, Yoel; Izhaky, Nahum; Paniccia, Mario (2007). "High-speed optical modulation based on carrier depletion in a silicon waveguide". Optics Express. 15 (2): 660–668. Bibcode:2007OExpr..15..660L. doi:10.1364/OE.15.000660.
- Chen, Long; Preston, Kyle; Manipatruni, Sasikanth; Lipson, Michal (2009). "Integrated GHz silicon photonic interconnect with micrometer-scale modulators and detectors". Optics Express. 17 (17): 15248–15256. arXiv:0907.0022. Bibcode:2009OExpr..1715248C. doi:10.1364/OE.17.015248.
- Vance, Ashlee. "Intel cranks up next-gen chip-to-chip play". The Register. Retrieved 26 July 2009.
- Shainline, J. M.; Orcutt, J. S.; Wade, M. T.; Nammari, K.; Moss, B.; Georgas, M.; Sun, C.; Ram, R. J.; Stojanović, V.; Popović, M. A. (2013). "Depletion-mode carrier-plasma optical modulator in zero-change advanced CMOS". Optics Letters. 38 (15): 2657–2659. Bibcode:2013OptL...38.2657S. doi:10.1364/OL.38.002657. PMID 23903103.
- "Major silicon photonics breakthrough could allow for continued exponential growth in microprocessors". KurzweilAI. 8 October 2013.
- Shainline, J. M.; Orcutt, J. S.; Wade, M. T.; Nammari, K.; Tehar-Zahav, O.; Sternberg, Z.; Meade, R.; Ram, R. J.; Stojanović, V.; Popović, M. A. (2013). "Depletion-mode polysilicon optical modulators in a bulk complementary metal-oxide semiconductor process". Optics Letters. 38 (15): 2729–2731. Bibcode:2013OptL...38.2729S. doi:10.1364/OL.38.002729. PMID 23903125.
- Kucharski, D.; et al. (2010). "10 Gb/s 15mW optical receiver with integrated Germanium photodetector and hybrid inductor peaking in 0.13µm SOI CMOS technology". Solid-State Circuits Conference Digest of Technical Papers (ISSCC): 360–361.
- Gunn, Cary; Masini, Gianlorenzo; Witzens, J.; Capellini, G. (2006). "CMOS photonics using germanium photodetectors". ECS Transactions. 3 (7): 17–24. doi:10.1149/1.2355790.
- Vivien, Laurent; Rouvière, Mathieu; Fédéli, Jean-Marc; Marris-Morini, Delphine; Damlencourt, Jean François; Mangeney, Juliette; Crozat, Paul; El Melhaoui, Loubna; Cassan, Eric; Le Roux, Xavier; Pascal, Daniel; Laval, Suzanne (2007). "High speed and high responsivity germanium photodetector integrated in a Silicon-On-Insulator microwaveguide". Optics Express. 15 (15): 9843–9848. Bibcode:2007OExpr..15.9843V. doi:10.1364/OE.15.009843.
- "Monolithic germanium/silicon avalanche photodiodes with 340 GHz gain–bandwidth product". Nature Photonics. 3: 59–63. 2008. Bibcode:2009NaPho...3...59K. doi:10.1038/nphoton.2008.247.
- Modine, Austin (8 December 2008). "Intel trumpets world's fastest silicon photonic detector". The Register.
- Narasimha, A. (2008). "A 40-Gb/s QSFP optoelectronic transceiver in a 0.13 µm CMOS silicon-on-insulator technology". Proceedings of the Optical Fiber Communication Conference (OFC): OMK7. ISBN 978-1-55752-859-9.
- Doerr, Christopher R.; et al. (2015). "Silicon photonic integration in telecommunications". In Yamada, Koji. Photonic Integration and Photonics-Electronics Convergence on Silicon. Frontiers Media SA. p. 7. Bibcode:2015FrP.....3...37D. doi:10.3389/fphy.2015.00037.
- Orcutt, Jason; et al. (2016). Monolithic Silicon Photonics at 25Gb/s. Optical Fiber Communication Conference. OSA. pp. Th4H.1. doi:10.1364/OFC.2016.Th4H.1.
- Frederic, Boeuf; et al. (2015). Recent Progress in Silicon Photonics R&D and Manufacturing on 300mm Wafer Platform. Optical Fiber Communication Conference. OSA. pp. W3A.1. doi:10.1364/OFC.2015.W3A.1.
- Meindl, J. D. (2003). "Beyond Moore's Law: the interconnect era". Computing in Science & Engineering. 5 (1): 20–24. doi:10.1109/MCISE.2003.1166548.
- Barwicz, T.; Byun, H.; Gan, F.; Holzwarth, C. W.; Popovic, M. A.; Rakich, P. T.; Watts, M. R.; Ippen, E. P.; Kärtner, F. X.; Smith, H. I.; Orcutt, J. S.; Ram, R. J.; Stojanovic, V.; Olubuyide, O. O.; Hoyt, J. L.; Spector, S.; Geis, M.; Grein, M.; Lyszczarz, T.; Yoon, J. U. (2006). "Silicon photonics for compact, energy-efficient interconnects". Journal of Optical Networking. 6 (1): 63–73. Bibcode:2007JON.....6...63B. doi:10.1364/JON.6.000063.
- Orcutt, J. S.; et al. (2008). Demonstration of an Electronic Photonic Integrated Circuit in a Commercial Scaled Bulk CMOS Process. Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference and Photonic Applications Systems Technologies.
- Sun, Chen; et al. (2015). "Single-chip microprocessor that communicates directly using light". Nature. 528: 534–538. Bibcode:2015Natur.528..534S. doi:10.1038/nature16454.
- Bowers, John E (2014). Semiconductor lasers on silicon. 2014 International Semiconductor Laser Conference\. IEEE. p. 29.
- "Hybrid Silicon Laser – Intel Platform Research". Intel. Retrieved 14 July 2009.
- Rong, H; Liu, A; Jones, R; Cohen, O; Hak, D; Nicolaescu, R; Fang, A; Paniccia, M (2005). "An all-silicon Raman laser". Nature. 433 (7023): 292–294. Bibcode:2005Natur.433..292R. doi:10.1038/nature03273. PMID 15635371.
- Borghino, Dario (13 December 2012). "IBM integrates optics and electronics on a single chip". Gizmag.com.
- Simonite, Tom. "Intel Unveils Optical Technology to Kill Copper Cables and Make Data Centers Run Faster | MIT Technology Review". Technologyreview.com. Retrieved 4 September 2013.
- Orcutt, Mike (2 October 2013) "Graphene-Based Optical Communication Could Make Computing More Efficient. MIT Technology Review.
- Analui, Behnam; Guckenberger, Drew; Kucharski, Daniel; Narasimha, Adithyaram (2006). "A Fully Integrated 20-Gb/s Optoelectronic Transceiver Implemented in a Standard 0.13- μm CMOS SOI Technology". IEEE Journal of Solid-State Circuits. 41 (12): 2945–2955. Bibcode:2006IJSSC..41.2945A. doi:10.1109/JSSC.2006.884388.
- Boyraz, ÖZdal; Koonath, Prakash; Raghunathan, Varun; Jalali, Bahram (2004). "All optical switching and continuum generation in silicon waveguides". Optics Express. 12 (17): 4094–4102. Bibcode:2004OExpr..12.4094B. doi:10.1364/OPEX.12.004094.
- Vlasov, Yurii; Green, William M. J.; Xia, Fengnian (2008). "High-throughput silicon nanophotonic wavelength-insensitive switch for on-chip optical networks". Nature Photonics. 2 (4): 242–246. doi:10.1038/nphoton.2008.31.
- Foster, Mark A.; Turner, Amy C.; Salem, Reza; Lipson, Michal; Gaeta, Alexander L. (2007). "Broad-band continuous-wave parametric wavelength conversion in silicon nanowaveguides". Optics Express. 15 (20): 12949–12958. Bibcode:2007OExpr..1512949F. doi:10.1364/OE.15.012949.
- "After six years of planning, Compass-EOS takes on Cisco to make blazing-fast routers". venturebeat.com. 12 March 2013. Retrieved 25 April 2013.
- Zortman, W. A. (2010). "Power penalty measurement and frequency chirp extraction in silicon microdisk resonator modulators". Proc. Optical Fiber Communication Conference (OFC) (OMI7).
- Biberman, Aleksandr; Manipatruni, Sasikanth; Ophir, Noam; Chen, Long; Lipson, Michal; Bergman, Keren (2010). "First demonstration of long-haul transmission using silicon microring modulators". Optics Express. 18 (15): 15544–15552. Bibcode:2010OExpr..1815544B. doi:10.1364/OE.18.015544.
- Bourzac, Katherine (2015-06-11). "Can Magic Leap Do What It Claims with $592 Million?". MIT Technology Review. Retrieved 2015-06-13.
- "Silicon (Si)". University of Reading Infrared Multilayer Laboratory. Retrieved 17 July 2009.
- Yin, Lianghong; Lin, Q.; Agrawal, Govind P. (2006). "Dispersion tailoring and soliton propagation in silicon waveguides". Optics Letters. 31 (9): 1295–1297. Bibcode:2006OptL...31.1295Y. doi:10.1364/OL.31.001295.
- Turner, Amy C.; Manolatou, Christina; Schmidt, Bradley S.; Lipson, Michal; Foster, Mark A.; Sharping, Jay E.; Gaeta, Alexander L. (2006). "Tailored anomalous group-velocity dispersion in silicon channel waveguides". Optics Express. 14 (10): 4357–4362. Bibcode:2006OExpr..14.4357T. doi:10.1364/OE.14.004357.
- Agrawal, Govind P. (1995). Nonlinear fiber optics (2nd ed.). San Diego (California): Academic Press. ISBN 0-12-045142-5.
- Malitson, I. H. (1965). "Interspecimen Comparison of the Refractive Index of Fused Silica". Journal of the Optical Society of America. 55 (10): 1205–1209. doi:10.1364/JOSA.55.001205.
- Celler, G. K.; Cristoloveanu, Sorin (2003). "Frontiers of silicon-on-insulator". Journal of Applied Physics. 93 (9): 4955. Bibcode:2003JAP....93.4955C. doi:10.1063/1.1558223.
- Koos, C; Jacome, L; Poulton, C; Leuthold, J; Freude, W (2007). "Nonlinear silicon-on-insulator waveguides for all-optical signal processing". Optics Express. 15 (10): 5976–5990. Bibcode:2007OExpr..15.5976K. doi:10.1364/OE.15.005976. PMID 19546900.
- Foster, M. A.; Turner, A. C.; Sharping, J. E.; Schmidt, B. S.; Lipson, M; Gaeta, A. L. (2006). "Broad-band optical parametric gain on a silicon photonic chip". Nature. 441 (7096): 960–3. Bibcode:2006Natur.441..960F. doi:10.1038/nature04932. PMID 16791190.
- Griffith, Austin G.; Lau, Ryan K.W.; Cardenas, Jaime; Okawachi, Yoshitomo; Mohanty, Aseema; Fain, Romy; Lee, Yoon Ho Daniel; Yu, Mengjie; Phare, Christopher T.; Poitras, Carl B.; Gaeta, Alexander L.; Lipson, Michal (24 February 2015). "Silicon-chip mid-infrared frequency comb generation". Nature Communications. 6: 6299. arXiv:1408.1039. Bibcode:2015NatCo...6E6299G. doi:10.1038/ncomms7299. PMID 25708922.
- Kuyken, Bart; Ideguchi, Takuro; Holzner, Simon; Yan, Ming; Hänsch, Theodor W.; Van Campenhout, Joris; Verheyen, Peter; Coen, Stéphane; Leo, Francois; Baets, Roel; Roelkens, Gunther; Picqué, Nathalie (20 February 2015). "An octave-spanning mid-infrared frequency comb generated in a silicon nanophotonic wire waveguide". Nature Communications. 6: 6310. arXiv:1405.4205. Bibcode:2015NatCo...6E6310K. doi:10.1038/ncomms7310. PMC 4346629. PMID 25697764.
- Panoiu, Nicolae C.; Chen, Xiaogang; Osgood Jr., Richard M. (2006). "Modulation instability in silicon photonic nanowires". Optics Letters. 31 (24): 3609–11. Bibcode:2006OptL...31.3609P. doi:10.1364/OL.31.003609. PMID 17130919.
- Yin, Lianghong; Agrawal, Govind P. (2006). "Impact of two-photon absorption on self-phase modulation in silicon waveguides: Free-carrier effects". Optics Letters. 32 (14): 2031–2033. Bibcode:2007OptL...32.2031Y. doi:10.1364/OL.32.002031.
- Nikbin, Darius (20 July 2006). "Silicon photonics solves its "fundamental problem"". IOP publishing.
- Rybczynski, J.; Kempa, K.; Herczynski, A.; Wang, Y.; Naughton, M. J.; Ren, Z. F.; Huang, Z. P.; Cai, D.; Giersig, M. (2007). "Two-photon absorption and Kerr coefficients of silicon for 850– 2,200 nmi (4,100 km)". Applied Physics Letters. 90 (2): 191104. Bibcode:2007ApPhL..90b1104R. doi:10.1063/1.2430400.
- Tsia, K. M. (2006). Energy Harvesting in Silicon Raman Amplifiers. 3rd IEEE International Conference on Group IV Photonics.
- Soref, R.; Bennett, B. (1987). "Electrooptical Effects in Silicon". IEEE Journal of Quantum Electronics. 23 (1): 123–129. Bibcode:1987IJQE...23..123S. doi:10.1109/JQE.1987.1073206.
- Liu, Y.; Tsang, H. K. (2006). "Nonlinear absorption and Raman gain in helium-ion-implanted silicon waveguides". Optics Letters. 31 (11): 1714–1716. Bibcode:2006OptL...31.1714L. doi:10.1364/OL.31.001714.
- Zevallos l., Manuel E.; Gayen, S. K.; Alrubaiee, M.; Alfano, R. R. (2005). "Lifetime of photogenerated carriers in silicon-on-insulator rib waveguides". Applied Physics Letters. 86: 071115. Bibcode:2005ApPhL..86a1115Z. doi:10.1063/1.1846145.
- Jones, Richard; Rong, Haisheng; Liu, Ansheng; Fang, Alexander W.; Paniccia, Mario J.; Hak, Dani; Cohen, Oded (2005). "Net continuous wave optical gain in a low loss silicon-on-insulator waveguide by stimulated Raman scattering". Optics Express. 13 (2): 519–525. Bibcode:2005OExpr..13..519J. doi:10.1364/OPEX.13.000519.
- Manipatruni, Sasikanth; et al. (2007). "High Speed Carrier Injection 18 Gbit/s Silicon Micro-ring Electro-optic Modulator". Proceedings of Lasers and Electro-Optics Society: 537–538. doi:10.1109/leos.2007.4382517.
- Jacobsen, Rune S.; Andersen, Karin N.; Borel, Peter I.; Fage-Pedersen, Jacob; Frandsen, Lars H.; Hansen, Ole; Kristensen, Martin; Lavrinenko, Andrei V.; Moulin, Gaid; Ou, Haiyan; Peucheret, Christophe; Zsigri, Beáta; Bjarklev, Anders (2006). "Strained silicon as a new electro-optic material". Nature. 441 (7090): 199–202. Bibcode:2006Natur.441..199J. doi:10.1038/nature04706. ISSN 0028-0836. PMID 16688172.
- Avrutsky, Ivan; Soref, Richard (2011). "Phase-matched sum frequency generation in strained silicon waveguides using their second-order nonlinear optical susceptibility". Optics Express. 19 (22): 21707. Bibcode:2011OExpr..1921707A. doi:10.1364/OE.19.021707. ISSN 1094-4087.
- Cazzanelli, M.; Bianco, F.; Borga, E.; Pucker, G.; Ghulinyan, M.; Degoli, E.; Luppi, E.; Véniard, V.; Ossicini, S.; Modotto, D.; Wabnitz, S.; Pierobon, R.; Pavesi, L. (2011). "Second-harmonic generation in silicon waveguides strained by silicon nitride". Nature Materials. 11 (2): 148–154. Bibcode:2012NatMa..11..148C. doi:10.1038/nmat3200. ISSN 1476-1122. PMID 22138793.
- Alloatti, L.; Korn, D.; Weimann, C.; Koos, C.; Freude, W.; Leuthold, J. (2012). "Second-order nonlinear silicon-organic hybrid waveguides". Optics Express. 20 (18): 20506. Bibcode:2012OExpr..2020506A. doi:10.1364/OE.20.020506. ISSN 1094-4087.
- Hon, Nick K.; Tsia, Kevin K.; Solli, Daniel R.; Jalali, Bahram (2009). "Periodically poled silicon". Applied Physics Letters. 94 (9): 091116. arXiv:0812.4427. Bibcode:2009ApPhL..94i1116H. doi:10.1063/1.3094750. ISSN 0003-6951.
- Van Laer, Raphaël; Kuyken, Bart; Van Thourhout, Dries; Baets, Roel (2015-03-01). "Interaction between light and highly confined hypersound in a silicon photonic nanowire". Nature Photonics. 9 (3): 199–203. arXiv:1407.4977. Bibcode:2015NaPho...9..199V. doi:10.1038/nphoton.2015.11. ISSN 1749-4885.
- Kittlaus, Eric A.; Shin, Heedeuk; Rakich, Peter T. (2016-07-01). "Large Brillouin amplification in silicon". Nature Photonics. 10 (7): 463–467. arXiv:1510.08495. Bibcode:2016NaPho..10..463K. doi:10.1038/nphoton.2016.112. ISSN 1749-4885.
- Van Laer, Raphaël; Bazin, Alexandre; Kuyken, Bart; Baets, Roel; Thourhout, Dries Van (2015-01-01). "Net on-chip Brillouin gain based on suspended silicon nanowires". New Journal of Physics. 17 (11): 115005. arXiv:1508.06318. Bibcode:2015NJPh...17k5005V. doi:10.1088/1367-2630/17/11/115005. ISSN 1367-2630.
- Van Laer, Raphaël; Baets, Roel; Van Thourhout, Dries (2016-05-20). "Unifying Brillouin scattering and cavity optomechanics". Physical Review A. 93 (5): 053828. arXiv:1503.03044. Bibcode:2016PhRvA..93e3828V. doi:10.1103/PhysRevA.93.053828.
- Kobyakov, Andrey; Sauer, Michael; Chowdhury, Dipak (2010-03-31). "Stimulated Brillouin scattering in optical fibers". Advances in Optics and Photonics. 2 (1). Bibcode:2010AdOP....2....1K. doi:10.1364/AOP.2.000001. ISSN 1943-8206.
- Levy, Shahar; Lyubin, Victor; Klebanov, Matvei; Scheuer, Jacob; Zadok, Avi (2012-12-15). "Stimulated Brillouin scattering amplification in centimeter-long directly written chalcogenide waveguides". Optics Letters. 37 (24): 5112. Bibcode:2012OptL...37.5112L. doi:10.1364/OL.37.005112. ISSN 1539-4794.
- Drazin, P. G. & Johnson, R. S. (1989). Solitons: an introduction. Cambridge University Press. ISBN 0-521-33655-4.