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OSA Seminar
April 21, 201611:30 am – 12:30 pm (CDT)

OSA Seminar


Barnabas Kim



Mitchell Physics Building

College Station, Texas 77843-4242

Event Details

Optics News

Magnetic-Free Non-Reciprocity Based on Staggered Commutation
Speaker: Hector Perez

Lorentz reciprocity is a fundamental characteristic of the vast majority of electronic and photonic structures. However, non-reciprocal components such as isolators, circulators and gyrators enable new applications ranging from radio frequencies to optical frequencies, including full-duplex wireless communication and on-chip all-optical information processing. Such components today dominantly rely on the phenomenon of Faraday rotation in magneto-optic materials. However, they are typically bulky, expensive and not suitable for insertion in a conventional integrated circuit. Here we demonstrate magnetic-free linear passive non-reciprocity based on the concept of staggered commutation. Commutation is a form of parametric modulation with very high modulation ratio. We observe that staggered commutation enables time-reversal symmetry breaking within very small dimensions (λ/1,250 * λ/1,250 in our device), resulting in a miniature radio-frequency circulator that exhibits reduced implementation complexity, very low loss, strong non-reciprocity, significantly enhanced linearity and real-time reconfigurability, and is integrated in a conventional complementary metal-oxide-semiconductor integrated circuit for the first time.

Main Talk

Steady-State Quantum Coherence in Fano-Agarwal-Zhu-Scully Coupling System
Speaker: Barnabas Kim

In quantum systems, quantum coherence causes many interesting effects: Lasing without Inversion, Inversion without lasing, refractive index enhancement via quantum coherence, and so on. In density matrix formalism, quantum coherence is expressed as the off-diagonal term, which suggests simultaneous populations between two coherent states. However, in thermal system these quantum coherence has been usually vanished since the residing thermal noise. But, the system in Fano-Agarwal-ZhuScully coupling might get a coherence coupling between states. Here, we will check whether this quantum coherence can be maintained in a system, which is immersed in thermal bath. And, we also show the power efficiency improvement in a model for photo solar cell and photosynthetic cell, which has caused by this quantum coherence.

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