A super-channel is an evolution in

dense wavelength-division multiplexing In fiber-optic communications, wavelength-division multiplexing (WDM) is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths (i.e., colors) of laser light. This techni ...

(DWDM) in which multiple,

coherent Coherence, coherency, or coherent may refer to the following: Physics * Coherence (physics), an ideal property of waves that enables stationary (i.e. temporally and spatially constant) interference * Coherence (units of measurement), a deri ...

optical carriers are combined to create a unified channel of a higher data rate, and which is brought into service in a single operational cycle.

Background

From around the year 2010, coherent optical transmission at 40Gbit/s and 100Gbit/s began to be deployed in long-haul optical networks around the world. Coherent technology enables higher data rates to be sent over long haul (typically >2,000 km) optical transmission networks, compared to the historical modulation and detection technique, Intensity Modulation with Direct Detection (sometimes referred to as Non-Return to Zero, NRZ or On/Off Keying, OOK), which had been widely used for several decades. However, a coherent detector requires that the incoming phase modulation information is digitized before being sent to a high-performance

digital signal processor A digital signal processor (DSP) is a specialized microprocessor chip, with its architecture optimized for the operational needs of digital signal processing. DSPs are fabricated on MOS integrated circuit chips. They are widely used in audio si ...

(DSP). Within the DSP, optical impairments such as

chromatic dispersion In optics, and by analogy other branches of physics dealing with wave propagation, dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency; sometimes the term chromatic dispersion is used for specificity to ...

and

polarization mode dispersion Polarization mode dispersion (PMD) is a form of modal dispersion where two different polarizations of light in a waveguide, which normally travel at the same speed, travel at different speeds due to random imperfections and asymmetries, causing ...

can be compensated for. Digitizing the received signal requires an extremely high speed

analog-to-digital converter In electronics, an analog-to-digital converter (ADC, A/D, or A-to-D) is a system that converts an analog signal, such as a sound picked up by a microphone or light entering a digital camera, into a digital signal. An ADC may also provide ...

(ADC) capability. Current commercially deployed coherent products are limited to 200 Gbit/s per optical carrier. Going beyond 200 Gbit/s per WDM channel requires the use of multiple carriers to make up a single WDM interface. The resulting multiplex, called a super-channel (or superchannel), creates a multi-wavelength signal in which each wavelength will operate at the maximum data rate permitted by commercially available ADC components. The primary advantages of a super-channel approach are increased spectral efficiency (a consequence of both coherent detection and the possibility of tight spectral packing of the subcarriers making up a super-channel), and operational scalability (the ability to bring larger units of long haul optical capacity into service for a given operational effort).

Introduction about super-channels

The major difference between superchannel and conventional WDM is the channel gap. Any technique which can reduce the channel gap close to the Nyquist bandwidth (equal signal baud) can be attributed to "superchannel transmission system". These techniques include orthogonal-band-multiplexed (OBM)-orthogonal frequency-division multiplexing (OFDM), no-guard-interval (NGI)-OFDM, Nyquist WDM, multi-channel equalization (MCE)-WDM (also named as Joint ICI Cancellation)

Examples of super-channels

Early work on DWDM super-channels included attempts using multiple laser sources, and wavelength combs generated from a single source – a form of optical

orthogonal frequency-division multiplexing In telecommunications, orthogonal frequency-division multiplexing (OFDM) is a type of digital transmission and a method of encoding digital data on multiple carrier frequencies. OFDM has developed into a popular scheme for wideband digital commun ...

(Optical OFDM). The first experimental demonstration of long-haul superchannel transmission, which coined the term `superchannel' for this type of application, was performed by

Bell Labs Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial research and scientific development company owned by mult ...

' S. Chandrasekhar and X. Liu in 2009. The approach being brought to market by companies such as

Infinera Infinera Corporation is a San Jose, California-based vertically integrated manufacturer of Wavelength division multiplexing (WDM)-based packet optical transmission equipment and IP transport technologies for the telecommunications service provide ...

Alcatel-Lucent Alcatel–Lucent S.A. () was a French–American global telecommunications equipment company, headquartered in Boulogne-Billancourt, France. It was formed in 2006 by the merger of France-based Alcatel and U.S.-based Lucent, the latter being a su ...

Huawei Huawei Technologies Co., Ltd. ( ; ) is a Chinese multinational technology corporation headquartered in Shenzhen, Guangdong, China. It designs, develops, produces and sells telecommunications equipment, consumer electronics and various smar ...

and

Ciena Ciena Corporation is an American telecommunications networking equipment and software services supplier based in Hanover, Maryland. The company has been described by ''The Baltimore Sun'' as the "world's biggest player in optical connectivity." T ...

makes use of multiple laser sources. Infinera is making use of their large scale

photonic integrated circuit A photonic integrated circuit (PIC) or integrated optical circuit is a microchip containing two or more photonic components which form a functioning circuit. This technology detects, generates, transports, and processes light. Photonic integrated c ...

(PIC) technology, while the other system vendors are building super-channel line cards using predominantly discrete optical components. The Infinera super-channel solution was first deployed in mid-2012, and consists of a ten-carrier, 500-Gbit/s Polarization Multiplexed Quadrature Phase Shift Keying (PM-QPSK) super-channel implemented on a single line card. Infinera has also demonstrated a ten-carrier PM-16QAM super-channel solution that is intended to fit in the same form factor as the current 500-Gbit/s product. Infinera claims over twenty customer deployments of this technology worldwide. Nortel (now Ciena) first commercialized a PM-BPSK 50 Gb/s and PM-QPSK 100 Gb/s super-channel transceiver in late 2009. Alcatel-Lucent, Ciena and Huawei have all announced dual carrier, 200-Gbit/s PM-QPSK super-channel designs that can also operate at 400 Gbit/s using a shorter optical reach PM-16QAM modulation. The first commercial deployment of a 400-Gbit/s superchannel used the

400G Photonic Service Engine (PSE) on an Orange Network.

Notes and references

* S. Chandrasekhar, X. Liu, B. Zhu, and D. Peckham, “Transmission of a 1.2-Tb/s 24-Carrier No-Guard-Interval Coherent OFDM Superchannel over 7200-km of Ultra-Large-Area Fiber”, Post deadline paper PD 2.6, ECOC 2009, Vienna, Austria, September 20–24 (2009). * Govind P. Agrawal : “Fiber-Optic Communication Systems, 4th Edition.” (2010). * Gabriella Bosco et al.: “On the Performance of Nyquist-WDM Terabit Superchannels Based on PM BPSK, PM-QPSK, PM-8QAM or PM-16QAM Subcarriers”. Journal of Lightwave Technology, Vol. 29, No. 1, January 1, 2011. * W. Shieh, Q. Yang, and Y. Ma, “107 Gb/s coherent optical OFDM transmission over 1000-km SSMF fiber using orthogonal band multiplexing,” Opt Express, 16(9), 6378-6386 (2008), http://www.opticsinfobase.org/oe/fulltext.cfm?uri=oe-16-9-6378&id=157340 * A.Sano, E.Yamada, H.Masuda, E.Yamazaki, T.Kobayashi, E.Yoshida,Y.Miyamoto, R.Kudo, Ko.Ishihara, and Y.Takatori “No-guard-interval coherent optical OFDM for 100-Gbs long-haul WDM transmission,” J. Lightwave Technol. 27, 3705-3713 (2009) * X.Zhou, L.E.Nelson, P.Magill, R.Isaac, B.Zhu, D.W.Peckham, P.I.Borel, and K.Carlson, “PDM-Nyquist-32QAM for 450-Gb/s per-channel WDM transmission on the 50 GHz ITU-T grid,” J. Lightwave Technol. 30, 553 – 559 (2012) * C.Liu, J.Pan, T.Detwiler, A.Stark, Y.T.Hsueh G.K.Chang, and S.E.Ralph “Super receiver design for superchannel coherent optical systems,” Proc. SPIE, 8284, 1–8(2012). * Zeng, Tao. "Superchannel transmission system based on multi-channel equalization." Optics express 21.12 (2013): 14799–14807. http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-21-12-14799 * Light Reading: “Infinera Claims Top 100G Share”. http://www.lightreading.com/long-haul-wdm-equipment/infinera-claims-top-100g-share/240143572 *Light Reading: "Verizon Switches On 100G in Europe". http://www.lightreading.com/ethernet-ip/verizon-switches-on-100g-in-europe/d/d-id/673196 * Light Reading: "Huawei Unveils New WDM Prototype". http://www.lightreading.com/optical-equipment/huawei-unveils-new-wdm-prototype/240140353 * Light Reading: "AlcaLu Claims 400G is Hot". http://www.lightreading.com/optical-equipment/alcalu-claims-400g-is-hot/240140479 * Light Reading: "Beyond 100G: Optical Vendors Push for 400G". http://www.lightreading.com/beyond-100g-optical-vendors-push-for-400g/240145009 * Alcatel-Lucent's 400G PSE super-channel product, commercially available since 2013. https://www.alcatel-lucent.com/innovation/400g-pse {{DEFAULTSORT:Super-channel Photonics