physics

Super-channel

Super-channel is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Super-channel rather than just read about it. In short: A super-channel is an evolution in dense wavelength-division multiplexing (DWDM) in which multiple, coherent 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 2010, coherent optical transmission at 40 Gbit/s and 100 Gbit/s began to be deployed in long-haul optical networks around the world.

Key takeaways

Super-channel belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Super-channel to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Super-channel from memory before moving on to harder problems.

Reference excerpt

A super-channel is an evolution in dense wavelength-division multiplexing (DWDM) in which multiple, coherent 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 2010, coherent optical transmission at 40 Gbit/s and 100 Gbit/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 (DSP). Within the DSP, optical impairments such as chromatic dispersion and polarization mode dispersion can be compensated for. Digitizing the received signal requires an extremely high speed analog-to-digital converter (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 (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' S. Chandrasekhar and X. Liu in 2009. The approach being brought to market by companies such as Infinera, Alcatel-Lucent, Huawei and Ciena makes use of multiple laser sources. Infinera is making use of their large scale photonic integrated circuit (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 Alcatel-Lucent 400G Photonic Service Engine (PSE) on an Orange Network.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Super-channel

Start with the simplest possible case. Write down what Super-channel claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Super-channel before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Super-channel ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Super-channel

In research: Super-channel appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Super-channel in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Super-channel is common in secondary-school and first-year university syllabi. It links to neighbouring topics Optical communications, Photonics, Telecommunications engineering, so understanding it makes those chapters shorter.
In everyday life: Look for Super-channel outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Super-channel” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Super-channel in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Super-channel means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Super-channel out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Super-channel in simple terms?

Why does Super-channel matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Super-channel?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Super-channel.