Optical isolation created by indirect interband photonic transitions

An interferometer, comprising:

• a first and a second photonic structure coupled to the at least first photonic structure at two coupler regions, said first photonic structure having two separate photonic bands and a refractive index;
• and
• a device modulating the refractive index of the first photonic structure, so that light supplied to the first photonic structure and initially in a first one of the photonic bands traveling along a forward direction in the at least first photonic structure is converted to light in a second one of the photonic bands, and light in the first photonic band traveling along a backward direction opposite to the forward direction in the at least first photonic structure is not converted and remains in the first photonic band;
• wherein light supplied to a first end of the first photonic structure and initially in the first photonic band traveling along a forward direction in the photonic structures will pass to a second end of the first photonic structure, and light supplied to the second end of the first photonic structure and traveling along a backward direction in the photonic structures will pass to a first end of the second photonic structure.

A method for modulating light, comprising:

• providing at least one photonic structure that has two separate photonic bands, said at least one photonic structure having a refractive index;
• and
• supplying light initially in a first one of the photonic bands to the at least one photonic structure and traveling along a forward direction in the at least one photonic structure;
• modulating the refractive index of the at least one photonic structure, so that the light traveling along a forward direction in the at least one photonic structure is converted to light in a second one of the photonic bands, so that the at least a first photonic structure is non-reciprocal with respect to light traveling in the forward and backward directions;
• and
• supplying to the at least one photonic structure light in the first photonic band traveling along a backward direction opposite to the forward direction in the at least one photonic structure, such light remaining in the first photonic band without being converted.

A method for modulating light in an interferometer, comprising a first and a second photonic structure coupled to the at least first photonic structure at two coupler regions, said first photonic structure having two separate photonic bands and a refractive index;

• said method comprising:
• supplying to the first photonic structure light initially in a first one of the photonic bands traveling along a forward direction in the at least first photonic structure;
• modulating the refractive index of the first photonic structure, so that light initially in the first one of the photonic bands is converted to light in a second one of the photonic bands, and light in the first photonic band traveling along a backward direction opposite to the forward direction in the at least first photonic structure is not converted and remains in the first photonic band;
• wherein light supplied to a first end of the first photonic structure and initially in the first photonic band traveling along a forward direction in the photonic structures will pass to a second end of the first photonic structure, and light supplied to the second end of the first photonic structure and traveling along a backward direction in the photonic structures will pass to an end of the second photonic structure.