A novel apparatus for bonding of two polished substrates includes a plasma source in a ultra-high vacuum (UHV) chamber and a wafer-guiding element to control and guide wafers in the UHV chamber, where after a plasma activation process the wafers are guided and pressed against each other to form a covalent bond between wafer surfaces. The plasma activation process involves deposition of mono-layer or sub-monolayer metallic atom on the surface of substrates. After deposition of metallic layers, a high-force actuation presses the wafers and forms a covalent bond between the wafers. Then, the bonded wafer pair is ion-sliced or thinned to form single crystalline optical thin film. An annealing process oxidizes the deposited metallic layers and produces optically-transparent single crystalline thin film. An optical waveguide may be fabricated by this thin film while utilizing an electro-optic effect to produce optical modulators and other photonic devices.

An optical element includes an optical waveguide layer. The optical waveguide includes a periodic structure of grooves. The optical waveguide layer has a layer-thickness equal to or greater than 1.5 m and is made of material selected from a group consisting of Ta2O5, Al2O3, LiNbO3, LiTaO3, AlN, GaN, SiC, and Yttrium aluminum garnet (YAG). (D/0.5)2.5 is satisfied where D indicates the depth of groove; and indicates the pitch of the arranged grooves in the periodic structure. The unit of is identical to the unit of D.

A photonic integrated circuit and a method of fabrication are provided which includes: a substrate; a first optical waveguide disposed, at least in part, extending across the substrate, the first optical waveguide being configured to transmit a first mode of light; and a second optical waveguide located at least partially over the first optical waveguide, the second optical waveguide being configured to transmit a second mode of light, wherein the first optical waveguide is vertically coupled to the second optical waveguide through a third optical waveguide disposed below the second waveguide.

A method for manufacturing a waveguide aperture to block stray light from a facet of an integrated optical device include obtaining a wafer with one or more integrated optical devices formed thereon and with a cleaved facet; positioning a mask in front of the cleaved facet, thereby masking at least a portion of the waveguide aperture of at least one the one or more integrated optical devices; and applying a light-blocking coating to the cleaved facet with the mask masking the portion of each of the one or more integrated optical devices.

A novel apparatus for bonding of two polished substrates includes a plasma source in a ultra-high vacuum (UHV) chamber and a wafer-guiding element to control and guide wafers in the UHV chamber, where after a plasma activation process the wafers are guided and pressed against each other to form a covalent bond between wafer surfaces. The plasma activation process involves deposition of mono-layer or sub-monolayer metallic atom on the surface of substrates. After deposition of metallic layers, a high-force actuation presses the wafers and forms a covalent bond between the wafers. Then, the bonded wafer pair is ion-sliced or thinned to form single crystalline optical thin film. An annealing process oxidizes the deposited metallic layers and produces optically-transparent single crystalline thin film. An optical waveguide may be fabricated by this thin film while utilizing an electro-optic effect to produce optical modulators and other photonic devices.

A photonic chip and a preparation method thereof are provided. The chip includes a lithium niobate film modulator array, a first optical coupling array, and a silica waveguide wavelength-division multiplexer, and the lithium niobate film modulator array includes one or more lithium niobate film modulators and is used to modulate an optical signal; the first optical coupling array includes one or more first optical coupling structures, and the first optical coupling structure has one end connected to a corresponding lithium niobate thin film modulator and the other end connected to the silica waveguide wavelength-division multiplexer so as to transmit the modulated optical signal to the silica waveguide wavelength-division multiplexer; and the silica waveguide wavelength-division multiplexer is used to perform wavelength-division multiplexing on the modulated optical signal.

In an example, an integrated optical circuit (IOC) includes a first substrate formed of a first material and a first waveguide formed of a second material and positioned on the first substrate. The first waveguide includes a plurality of branches and is configured to polarize light beams that propagate through the first waveguide. The IOC further includes a second substrate formed of a third material, the second substrate coupled to or positioned on the first substrate. The IOC further includes a plurality of straight waveguides formed in the second substrate, each of the plurality of straight waveguides optically coupled to a respective branch of the plurality of branches of the first waveguide. The IOC further includes a plurality of electrodes positioned proximate to the plurality of straight waveguides, the plurality of electrodes configured to modulate the phase of light beams that propagate through the plurality of straight waveguides.

In an optical waveguide element, an optical waveguide is formed on a substrate, the optical waveguide has a main waveguide that propagates signal light, a waveguide for unnecessary light that guides unnecessary light released from the main waveguide, and a waveguide for collecting unnecessary light to which the unnecessary light emitted from the waveguide for unnecessary light is introduced, the waveguide for unnecessary light is connected to the waveguide for collecting unnecessary light via a waveguide for connection, and a width of the waveguide for connection, which is a width in a direction that perpendicularly intersects a propagation direction of the unnecessary light, at a portion connected to the waveguide for collecting unnecessary light is set to be wider than a width at a portion connected to the waveguide for unnecessary light with the waveguide for connection.

An electro-optic modulator. The modulator is made as a plurality of discrete elements, and adjacent elements abut such that there are no free space optics between adjacent discrete elements. The modulator comprises a radio frequency, RF, element configured to modulate light passing through the element based on an electrical RF input. The plurality of discrete elements comprises a first set of discrete elements fabricated from thin film lithium niobate, TFLN, and a second set of discrete elements fabricated from silicon photonics, SiPh. The first set of discrete elements comprises the RF element.

An electro-optic waveguide device may include a slot waveguide including a lower high-refractive-index layer with a first refractive index and an upper high-refractive-index layer with a second refractive index, wherein the lower high-refractive-index layer and the upper high-refractive-index layer have conductivity and are disposed to face each other with a gap; and a slot part formed as a low-refractive-index layer, wherein the low-refractive-index layer is formed of a material producing an electro-optic effect and has a third refractive index lower than the first refractive index and the second refractive index, wherein the low-refractive-index layer is formed in the gap to come into contact with the lower high-refractive-index layer and the upper high-refractive-index layer, and wherein one of the lower high-refractive-index layer or the upper high-refractive-index layer includes a stretch stretching on both sides of a contact portion with the slot part in a width direction intersecting a transmission direction.