physics

Optical circulator

Optical circulator 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 Optical circulator rather than just read about it. In short: An optical circulator is a three- or four-port optical device designed such that light entering any port exits from the next. This means that if light enters port 1 it is emitted from port 2, but if some of the emitted light is reflected back to the circulator, it does not come out of port 1 but instead exits from port 3.

Key takeaways

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

Reference excerpt

An optical circulator is a three- or four-port optical device designed such that light entering any port exits from the next. This means that if light enters port 1 it is emitted from port 2, but if some of the emitted light is reflected back to the circulator, it does not come out of port 1 but instead exits from port 3. This is analogous to the operation of an electronic circulator. Fiber-optic circulators are used to separate optical signals that travel in opposite directions in an optical fiber, for example to achieve bi-directional transmission over a single fiber. Because of their high isolation of the input and reflected optical powers and their low insertion loss, optical circulators are widely used in advanced fiber-optic communications and fiber-optic sensor applications. Optical circulators are non-reciprocal optics, which means that changes in the properties of light passing through the device are not reversed when the light passes through in the opposite direction. This can only happen when the symmetry of the system is broken, for example by an external magnetic field. A Faraday rotator is another example of a non-reciprocal optical device, and indeed it is possible to construct an optical circulator based on a Faraday rotator.

History In 1965, Ribbens reported an early form of optical circulator that utilized a Nicol prism with a Faraday rotator. With the advent of fiber and guided-wave optics, waveguide-integrable and polarization-independent optical circulators were later introduced. The concept was later extended to silicon photonic waveguide systems. In 2016, Scheucher et al. have demonstrated a fiber-integrated optical circulator whose nonreciprocal behavior originated from the chiral interaction between a single 85Rb atom and the confined light in a whispering-gallery mode microresonator. The routing direction of the device is controlled by the internal quantum state of the atom and the device is able to route individual photons. In 2013, Davoyan and Engheta proposed a nanoscale plasmonic Y-circulator based on three dielectric waveguides interconnected with a magneto-optical junction with plasmonic nanorods.

Illustrations

Worked examples

Example 1 — a first encounter with Optical circulator

Start with the simplest possible case. Write down what Optical circulator 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 Optical circulator 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 Optical circulator 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 Optical circulator

In research: Optical circulator 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 Optical circulator 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: Optical circulator is common in secondary-school and first-year university syllabi. It links to neighbouring topics Optical components, so understanding it makes those chapters shorter.
In everyday life: Look for Optical circulator 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.

Affiliate

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

How to study Optical circulator in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Optical circulator 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 Optical circulator out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Optical circulator in simple terms?

Why does Optical circulator 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 Optical circulator?

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 Optical circulator.