Researchers develop a unique optical isolator

"Essentially, we developed a very effective photonic isolator, able to isolate 99.6% of the light," said Professor Tal Carmon, head of the research team. "If we send 1,000 light particles, the device will effectively isolate 996 photons and will only be missing 4. Such isolation efficiency is needed for applications that include quantum optical communication devices and construction. It also works well when the light of the two opposite directions is perceived simultaneously, it is compatible with the standard optical fiber technology, it can be reduced and it does not change the color of the light. "

Just as downstream swimming is faster than swimming upstream and biking with the wind behind you is faster than riding against the wind, the light also shifts with the 'tailwind' or 'downwind' countercurrent "depending on the medium in which it moves. The speed of light in the glbad, for example, is slower than its speed in the air. Likewise, two beams of light that move in opposite directions in the glbad or in any other material will advance at the same speed.

"At Technion, I also learned that the speed of light depends on the speed of the medium in which it travels," said Professor Carmon. "Precisely as a swimmer in a river – the speed of light against the movement of the medium is slower than its speed with the movement of the medium."

This effect was already described in 1849 by the French scientist Armond Fizeau, who showed, as a swimmer in a river, the speed of light in a current is faster than the light that rises a current. Fizeau's discovery had a significant impact on the development of Einstein's theory of special relativity.

Fizeau's drag can lead to significant applications in optics and computer science, its unique ability to differentiate beam propagation velocities an optical isolator – a device in which light entering from one side is blocked, while light entering on the other side is transmitted. Until now, a device in which opposite light beams are advancing at different speeds has not been built.

But now, for the first time, the Technion researchers have managed to build such a device. The spherical optical device rotates at high speed. Light beams are fed from opposite directions via a neighboring conical fiber. The light coming from the right moves along the circumference of the ball, in the direction of the rotation of the sphere, while the light coming from the left rotates in the opposite direction of the rotation and is therefore move more slowly. The new device is an optical isolator – it transmits light from the left and turns off light from the right. Another relevant effect here is resonance. Like a musical instrument that resonates at a specific frequency, light circulating circumferentially in the sphere resonates resonantly. However, the different speeds of the counter-circulating light cause these lights to counter-circulate to have different colors. In this way, the light entering on one side

echoes inside the sphere, circulating thousands of times in the sphere, until it is absorbed. . On the other hand, light entering through the opposite side of the isolator is non-resonant and therefore traverses the device virtually without being disturbed. In other words, the light moves with the device, resonates and is turned off, while light moving against the device is transmitted and continues. "

Professor Carmon noted that the device was built at the Technion glbad blowing shop. Was built from a glbad rod whose tip was melted into a ball of 1 millimeter radius.Light enters the insulator on both sides of a standard optical fiber, conical near the sphere to a diameter 100 times smaller The sphere, which serves as a resonator, rotates at a super-fast speed – the tip of the bullet travels at a speed of 300 km / h – and the light coming from the fiber turns inside the sphere.

One the technical challenges facing the research group were to maintain the ultra-short distance between the fiber – through which the light is delivered – and the spherical resonator constant.The distance of speed is a real challenge, device does not move, and represents a huge challenge when the sphere spins at such a high speed, "said Professor Carmon. So we looked for a way to force the fiber to move with the sphere, although the fiber and the sphere are not connected, which we finally did when designing the fiber so that it floats on the wind generated by the rotation of the sphere. In this way, if the device wobbles – what it does because of the fast spin – the fiber will oscillate with it and the distance between them will be preserved.In fact, the fiber actually flies over from rotating sphere to constant and self-illuminated nano-elevation "

Photo shows fiber (empty circle), rotating sphere tip (bottom, gray), and wind flow between them, on which the fiber floats.Fiber floats over the sphere while maintaining a distance of several tens of nanometers.

Professor Carmon hopes that this nanosecond opens the way to a new type of mechanical device based on relatively unexplored forces that dominate at the nanoscale 19659003] "Forces acting at such distances include the forces of Casimir and Van der Waals – very strong forces from quantum effects, which to date , were barely exploited in mechanical devices, in general, and in mechanical oscillators in particular "he said. "We have recently demonstrated, for the first time, lasers in which water waves mediate laser emission, and also, for the first time, micro-lasers where the sound mediates. laser emission. "

generate such vibration-based lasers where the restoring force is Casimir or Van der Waals. The use of their self-aligned nano-alignment separation method could also allow micro-electromechanical devices [MEMS] where the Casimir and Van der Waals forces will be used.

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Creation of the first laser & water-wave & # 39;