![]() In this construction, complete isolation is accomplished by combining the nonreciprocal frequency conversion process, as discussed above, with a filter that removes all the converted light. (This length is referred to as the coherence length l c below). Performance of such device is analyzed using coupled mode theory given the experimentally available modulation in silicon. Such effect can be used in MachZehnder interferometers to form optical isolators and circulators. By choosing an appropriate length of the modulation region, complete frequency conversion can be achieved in the forward direction, while no conversion occurs in the backward direction. Photonic transitions in waveguides can create nonreciprocal phase response for counterpropagating modes. A new design of an optical isolator based on photonic transitions in the interbands of a honeycomb structure that generates a dual negative refraction in a. Because of the energy conserving -function in (10), a singular behavior of the response functions is obtained in the vicinity of the critical points of the Brillouin zone (Van. to the promotion of electrons from occupied valence bands to empty conduction bands. Achieving on-chip optical signal isolation is a fundamental difficulty. The optical absorption in crystals is mostly due to interband transitions, i.e. optical isolation created by indirect interband photonic transitions. As a result, interband photonic transition process occurs only along the forward direction but not in the backward direction. Complete optical isolation created by indirect interband photonic transitions. Complete optical isolation created by indirect interband photonic transitions. Integrated photonic circuits demand dynamic optical isolation for advanced signal. Such a transition is highly nonreciprocal: the modulation breaks both time-reversal and spatial inversion symmetry. Based on the effects of photonic transitions, we show here that a linear, broadband and non-reciprocal isolation can be accomplished by spatial-temporal refractive index modulations that simultaneously impart frequency and wavevector shifts during the photonic transition process. When subject to a refractive index modulation that is both spatial and temporal dependent, as defined by a modulation frequency and a wave vector, the modes inside the waveguide can go through an interband transition 9. ![]() 8 used a silicon waveguide that supports two modes with opposite symmetries forming two photonic bands. 1(a) is based upon the recent discovery of complete optical isolation effect induced by dynamic modulation. ![]()
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