Defying conventional wisdom, researchers have uncovered a novel coupling mechanism involving leaky mode, previously has been considered unsuitable for high-density integration in photonic circuits. This unexpected finding opens new possibilities for dense photonic integration, revolutionizing the scalability and application of photonic chips in optical computing, quantum communication, light detection and ranging (LiDAR), optical metrology, and biochemical sensing.

In a recent Light Science & Application publication ("Anisotropic leaky-like perturbation with subwavelength gratings enables zero crosstalk"), Sangsik Kim, associate professor of electrical engineering at Korea Advanced Institute of Science and Technology (KAIST), and his students at Texas Tech University demonstrated that an anisotropic leaky wave can achieve zero crosstalk between closely spaced identical waveguides using subwavelength grating (SWG) metamaterials. This counter-intuitive discovery drastically increases the coupling length of transverse-magnetic (TM) mode, which has historically posed challenges due to its low confinement.

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