A disclosed multimode optical fiber comprises a core and a cladding surrounding the core. The core has an outer radius r.sub.1 in between 20 μm and 30 μm. The cladding includes a first outer cladding region having an outer radius r.sub.4a and a second outer cladding region having an outer radius r.sub.4b less than or equal to 45 μm. The second outer cladding region comprises silica-based glass doped with titania. The optical fiber further includes a primary coating with an outer radius r.sub.5 less than or equal to 80 μm, and a thickness (r.sub.5−r.sub.4) less than or equal to 30 μm. The optical fiber further includes a secondary coating with an outer radius r.sub.6 less than or equal to 100 μm. The secondary coating has a thickness (r.sub.6−r.sub.5) less than or equal to 30 μm, and a normalized puncture load greater than 3.6×10.sup.−3 g/micron.sup.2.

In the examples provided herein, an apparatus has a mode converter coupled to a first waveguide to convert light propagating in a first set of spatial modes along the first waveguide to a second set of spatial modes. The apparatus also has a second waveguide coupled to the mode converter, where the second set of spatial modes propagate along the second waveguide in a first direction away from the mode converter. Further, the apparatus includes a coupler to couple a portion of the light propagating in the second set of spatial modes out of the second waveguide. Additionally, the second waveguide has an end facet away from the mode converter to reduce back reflection of the light not coupled out of the second waveguide to the first waveguide.

A demultiplexer for use in a wavelength division multiplexed system. The demultiplexer comprises: an input waveguide, configured to receive a wavelength division multiplexed signal; a demultiplexing element, configured to demultiplex the multiplexed signal received from the input waveguide into a plurality of multi-mode demultiplexed signal components; a multi-mode output waveguide, the multi-mode output waveguide being coupled to the demultiplexing element and configured to receive one of the multi-mode demultiplexed signal components; and a splitter, coupled to the multi-mode output waveguide, and configured to split the received multi-mode demultiplexed signal component into two single-mode outputs.

Example implementations described herein are directed to a system involving one or more photonic integrated circuits having multi-mode waveguides and connected to a printed optical board through the use of multi-mode waveguide connectors described herein. The printed optical board can include an embedded multi-mode waveguide bus to facilitate optical signal to and from the photonic integrated circuits. The system can also include a chiplet such as a photonic integrated circuit with a single mode waveguide configured to connect to an optical fiber cable.

In at least one embodiment, the optoelectronic semiconductor device comprises a carrier, a first semiconductor laser configured to emit a first laser radiation and applied on the carrier, and a multi-mode waveguide configured to guide the first laser radiation and also applied on the carrier, wherein the multi-mode waveguide comprises at least one furcation and a plurality of branches connected by the at least one furcation.

A method includes defining a first waveguide in a first region of an optical device over a first dielectric layer over a silicon on insulator (SOI) substrate of the optical device and disposing a second dielectric layer on the first waveguide and the first dielectric layer of the optical device. The method also includes defining a second region on the second dielectric layer, the first dielectric layer, and the SOI substrate. The second region includes an integrated trench structure defined in the SOI substrate. The method further includes etching the second region to form an etched second region, disposing a third dielectric layer in the etched second region, and disposing a second waveguide on at least the third dielectric layer. The second waveguide is disposed to provide an optical coupling between the second waveguide and the first waveguide.

A sensing cable includes a first optical fiber, a second optical fiber that extends along the first optical fiber and that is spaced from the first optical fiber, and a transmitting material that includes an intervention portion present between the first optical fiber and the second optical fiber, the transmitting material being configured to transmit light from the first optical fiber to the second optical fiber through the intervention portion.

In a multi-chip module and method, the multi-chip module includes a carrier; a multimode optical waveguide formed on and/or in the carrier; a first and second chip disposed on the carrier and coupled to the multimode optical waveguide; wherein the first chip is configured to transmit light beams into the multimode optical waveguide; the multimode optical waveguide is configured to generate mixed light beams that are an at least partial superposition of the light beams; the second chip is configured to receive the mixed light beams from the multimode optical waveguide; and the second chip is configured to store a representation of the received mixed light beams as a transmission signature and/or as a cryptographic key in a memory associated with the second chip, and/or compare the representation of the received mixed light beams with a target representation stored in the memory associated with the second chip.

An integrated optical structure for multiplexing and/or demultiplexing an optical signal comprises a main waveguide having two parallel side surfaces, a first waveguide which meets the main waveguide at a first region on one of the two side surfaces, and a plurality of second waveguides which meet the main waveguide at a second region on one of the two side surfaces. The second region is spaced at a determined distance from the first region. The two side surfaces are arranged at a first angle relative to an extension direction of the first waveguide and a second angle relative to extension directions of the plurality of second waveguides. The optical structure further comprises one or more waveguide extension structures. Each waveguide extension structure is arranged adjacent to one of the two side surfaces of the main waveguide at a region that is different to the first and the second region.

A bricked sub-wavelength periodic waveguide and a modal adapter, power divider and polarization splitter that use the waveguide. The waveguide includes blocks disposed periodically with a period “L.sub.z” on a substrate and which alternate with a covering material. The first blocks have a width “a.sub.x” and the second blocks have a width “b.sub.x”, alternating on the substrate according to a period “L.sub.x”, the second blocks being shifted a distance “d.sub.z” the first blocks in the direction of propagation. A modal adapter, a power divider and a polarization splitter all use the periodic waveguide and can operate with larger wave periods without leaving the sub-wavelength regime.