Integration method of a large-scale silicon-based lithium niobate film electro-optic modulator array. By using the method, the difficulty of a fabrication process of a lithium niobate crystal layer is reduced, requirements on precision of bonding lithium niobate and silicon is reduced, and fabrication and bonding of the large-scale array lithium niobate crystal layer can be completed at one time, so that production efficiency of the silicon-based lithium niobate film electro-optic modulator array is greatly improved; through design and optimization of the structure of the silicon crystal layers, light can be naturally alternated and mutually transmitted in silicon waveguides and lithium niobate waveguides, and a high-performance electro-optic modulation effect of the lithium niobate film is achieved.

According to an example aspect of the present invention, there is provided an apparatus comprising a first and a second polarization beam splitter-rotator (140, 142), together arranged to split two incoming polarization encoded qubits into four first optical modes, the apparatus being configured to align polarizations of the four first optical modes, an interferometer stage (150) configured to obtain, from the four first optical modes, four second optical modes, and four detectors (160) arranged to receive at least one of the four second optical modes.

An integrated mode converter and multiplexer (/demultiplexer) is disclosed, which combines a multimode interference coupler (100), at least one phase-shifter (200) and a symmetrical Y-junction (300). The dispersion of the multimode interference coupler (100) is engineered through subwavelength structures in order to achieve a very wide bandwidth. Several phase-shifter (200) topologies for further bandwidth enhancement are disclosed, as well as architectures for multiplexing a greater number of optical modes.

A device for generating a key has a multimode interferometer which can be coupled to a light source and has a light path having an electro-optical material, the light path being configured to obtain light at an input side, influence the light under the influence of a locally varying refraction index of the electro-optical material and provide influenced light at an output side. The device has a receiver configured to receive the influenced light at the output side, and has an evaluator configured to perform an evaluation based on the influenced light and to generate the key based on the evaluation.

A method includes obtaining a Photonic Integrated Circuit (PIC) with a butt-joint between a first core and a second core, wherein the butt-joint includes a poor quality region, wherein the first core is associated with a first optical device and the second core is associated with a second optical device, and wherein the first optical device and the second optical device are each on the PIC; etching away at least part of the poor quality region to form an etch trench between the first core and the second core; and growing an interconnect core between the first core and the second core in the etch trench.

A multimode interferometer includes: a multimode waveguide mesa having a top face extending in a direction of a first axis, a first side face and a second side face that extend in the direction of the first axis, and a first end face and a second end face that are arranged in the direction of the first axis; and a waveguide mesa connected to the first end face at a port; first and second waveguide mesas connected to first and second ports on the second end face. The multimode waveguide mesa has a first side edge line shared by the top face and the first side face, and an end line shared by the top face and the first end face. The first side edge line forms an acute angle with the end line at an outer vertex where the first side edge line and the end line meet.

An optical interference modulator comprises a main input, a main output, an optical splitter connected to the main input, first and second MMI couplers, each with a first primary-end access port connected to the splitter; a second primary-end access port connected to the main output; a first secondary-end access port connected to a respective primary waveguide; and a second secondary-end access port connected to a respective secondary waveguide. A light reflector is arranged to reflect light incident from said primary and secondary waveguides back into the same respective waveguide such that light travelling through the respective waveguide from the respective secondary-end access port, after reflection, travels back to the same secondary-end access port. For the MMI couplers, at least one of the respective primary and secondary waveguides comprises a respective light phase modulating device arranged to modulate the phase of light travelling along the corresponding waveguide in either direction.

Systems, methods, and techniques for optofluidic analyte detection and analysis using multi-mode interference (MMI) waveguides are disclosed herein. In some embodiments, spatially and spectrally multiplexed optical detection of particles is implemented on an optofluidic platform comprising multiple analyte channels intersecting a single MMI waveguide. In some embodiments, multi-stage photonic structures including a first stage MMI waveguide for demultiplexing optical signals by spatially separating different wavelengths of light from one another may be implemented. In some embodiments, a second stage may use single-mode waveguides and/or MMI waveguides to create multi-spot patterns using the demultiplexed, spatially separated light output from the first stage. In some embodiments, liquid-core MMI (LC-MMI) waveguides that are tunable by replacing a liquid core, heating/cooling the liquid core, and/or deforming the LC-MMI to change its width may be implemented in one or more of the analyte detection/analysis systems disclosed herein.

An optical module according to one embodiment includes: an optical element having a first side, a second side, and a third side; a housing; a thermoelectric cooler with the optical element being mounted on the thermoelectric cooler; a driving circuit arranged on the side of the first side of the optical element; a first bonding pad arranged on the side of the second side of the optical element; and a first wiring pattern provided on the frame body of the housing and connected to the first bonding pad of the optical element through the first bonding wiring, wherein the thermoelectric cooler has a plurality of Peltier elements arranged with spacings. A spacing between the plurality of Peltier elements located on the side of the second side is narrower than a spacing between the plurality of Peltier elements located in the center of the optical element.

A high-speed and low-voltage electro-optical modulator based on a lithium niobate-silicon wafer. A silicon wafer is located above a lithium niobate wafer; a lithium niobate-silicon hybrid waveguide is formed by etching a silicon waveguide; and the power of light waves is differently distributed in the lithium niobate-silicon hybrid waveguide by changing the structure of the silicon waveguide. When higher power is distributed in the silicon waveguide, the high-speed and low-voltage electro-optical modulator is suitable for realizing a compact wave splitting function, a wave combining function and a thermo-optical modulation function; and when higher power is distributed in the lithium niobate waveguide, the high-speed and low-voltage electro-optical modulator is suitable for realizing a high-speed and low-voltage electro-optical modulation function. The present invention takes advantage of the lithium niobate and silicon material platforms respectively, and is suitable for high-speed and low-voltage electro-optical modulation.