Structures for an electro-optic modulator and methods of fabricating such structures. A first plurality of cavities are formed in a bulk semiconductor substrate. A passive waveguide arm includes a first core arranged over the first plurality of cavities. The passive waveguide arm has an input port and an output port that is spaced lengthwise from the input port. An epitaxial semiconductor layer is arranged over the bulk semiconductor substrate, and includes a second plurality of cavities. An active waveguide arm includes a second core that is arranged over the second plurality of cavities. The second core of the active waveguide arm is coupled with the input port of the first core of the passive waveguide arm, and the second core of the active waveguide arm is also coupled with the output port of the first core of the passive waveguide arm.

A novel phase shifter design for carrier depletion based silicon modulators, based on an experimentally validated model, is described. It is believed that the heretofore neglected effect of incomplete ionization will have a significant impact on ultra-responsive phase shifters. A low VL product of 0.3 V.cm associated with a low propagation loss of 20 dB/cm is expected to be observed. The phase shifter is based on overlapping implantation steps, where the doses and energies are carefully chosen to utilize counter-doping to produce an S-shaped junction. This junction has a particularly attractive VL figure of merit, while simultaneously achieving attractively low capacitance and optical loss. This improvement will enable significantly smaller Mach-Zehnder modulators to be constructed that nonetheless would have low drive voltages, with substantial decreases in insertion loss. The described fabrication process is of minimal complexity; in particular, no high-resolution lithographic step is required.

A method of fabricating an optical structure comprises providing a layer of single crystal crystalline silicon supported on an insulating surface of a silicon substrate; using etching to remove part of the silicon layer and define a side wall which is non-parallel to the insulating surface of the substrate; forming a layer of insulating material over the side wall; forming a further layer of silicon over at least the insulating material; and removing the silicon of the further layer to a level of the layer of silicon such that the layer of insulating material occupies a slot between a portion of silicon in the layer and a portion of silicon in the further layer, a thickness of the layer of insulating material defining a width of the slot.

Coupling modulation of an optical resonator employs a variable modal index to provide modulation of optical signal coupling. A coupling-modulated optical resonator includes an optical resonator having a coupled portion and a bus waveguide having a modulation section adjacent to and coextensive with and separated by a gap from the coupled portion. The modulation section is to modulate coupling of an optical signal between the optical resonator and the bus waveguide according to a variable difference between a modal index of the bus waveguide modulation section and a modal index of the optical resonator coupled portion.

An optoelectronic integrated circuit includes (i) a first back-to-back-junction component (BBJC) and a second BBJC that conform to a first fabrication pattern, where the first BBJC includes a first A-type p-n junction (APNJ) in series with a first B-type p-n junction (BPNJ), where the second BBJC includes a second APNJ in series with a second BPNJ, and (ii) an optical component conforming to a second fabrication pattern that superimposes the first fabrication pattern. The APNJs and BPNJs may be identified based overlapping with separate arms of the optical component. The optical component overlaps the APNJs and BPNJs to provide modulation to optical signals using the modulation voltage from the electrodes. The first APNJ, the first BPNJ, the second APNJ, and the second BPNJ are disposed along respective directions, where metal bridges may be used, to reduce an imbalance in the modulation of the optical signals resulting from a fabrication misalignment.

An optical modulator includes a p-type first semiconductor layer (102) formed on a clad layer (101), an insulating layer (103) formed on the first semiconductor layer (102), and an n-type second semiconductor layer (104) formed on the insulating layer (103). The first semiconductor layer (102) is made of silicon or silicon-germanium, and the second semiconductor layer (104) is formed from a III-V compound semiconductor made of three or more materials.

A novel phase shifter design for carrier depletion based silicon modulators, based on an experimentally validated model, is described. It is believed that the heretofore neglected effect of incomplete ionization will have a significant impact on ultra-responsive phase shifters. A low VL product of 0.3 V.Math.cm associated with a low propagation loss of 20 dB/cm is expected to be observed. The phase shifter is based on overlapping implantation steps, where the doses and energies are carefully chosen to utilize counter-doping to produce an S-shaped junction. This junction has a particularly attractive VL figure of merit, while simultaneously achieving attractively low capacitance and optical loss. This improvement will enable significantly smaller Mach-Zehnder modulators to be constructed that nonetheless would have low drive voltages, with substantial decreases in insertion loss. The described fabrication process is of minimal complexity; in particular, no high-resolution lithographic step is required.

An optical modulating device may include a plurality of quantum dot (QD)-containing layers having QDs and a plurality of refractive index change layers. The QD-containing layers may be disposed between the refractive index change layers, respectively. The optical modulating device may be configured to modulate light-emission characteristics of the plurality of QD-containing layers. At least two of the QD-containing layers may have different central emission wavelengths. At least two of the plurality of refractive index change layers may include different materials or have different carrier densities.

An electro-optic device includes a first semiconductor layer including the rib-type waveguide, which includes a rib part and a first slab part, which extends in a first direction from the rib part; a dielectric layer, which is formed on the rib part; a second semiconductor layer, which extends in a second direction, which is opposite to the first direction, from an upper surface of the dielectric layer; a first high-concentration impurity region, which is formed in the first semiconductor layer to be in contact with the first slab part on the first direction side; and a second high-concentration impurity region, which is formed in a region of the second semiconductor layer on the second direction side. The second high-concentration impurity region is formed in a region other than a region overlapping the first semiconductor layer in a lamination direction.

An apparatus includes a silicon (Si) optical phase shifter. In an embodiment, the optical phase shifter comprises a planar optical waveguide having a silicon optical core, and a pair of biasing electrodes located along opposite sides of a segment of the silicon optical core. The segment of the silicon optical core comprises a series of p-n junctions. The series extends in a direction transverse to an optical propagation direction in a segment of the planar optical waveguide including the segment of the silicon optical core. At least two of the p-n junctions are configured to be reverse biased by applying a voltage across the biasing electrodes.