Abstract: Mapping of ports to other network components is generated by physically bending a fiber optic cable and then determining which optical network terminals experience a signal power loss (or receive attenuated signals) based on the bending. The physical bending can be done using a bending tool and the optical network terminals that experience the signal power loss can be identified using a back-end database operation. Generally, the correspondence between the physical bending and the power loss at the downstream components and or upstream components of the network is used to create the mapping of the ports at the splitter level.

Abstract: Structures including an edge coupler and methods of fabricating a structure including an edge coupler. The structure includes a waveguide core region on a first dielectric layer, and a second dielectric layer on the waveguide core region and the first dielectric layer. The waveguide core region has a tapered section with an end surface that terminates adjacent to an edge of the first dielectric layer. The second dielectric layer includes a first trench and a second trench that are each positioned adjacent to the tapered section of the waveguide core region.

Abstract: A waveguide heater is configured to heat an optical waveguide. The heater includes multiple heating elements and has one or two conditions selected from a group consisting of a first condition and the second condition. The first condition is the heater including multiple interior connectors that are each included in an interior electrical pathway between a pair of the heating elements where the interior connectors are connected in parallel and provide electrical communication between the heating elements included in the pair. The second condition is multiple exterior connectors that are each included in an exterior electrical pathway between electronics and a first one of the heating elements where the exterior connectors are connected in parallel and provide electrical communication between the electronics and the first heating element. The electronics are configured to apply an electrical bias to the heater. In some instances, the heater in included in a wavelength tuner.

Abstract: There are provided an optical fiber display system and an optical fiber changeover method each enabling an efficient optical fiber changeover work. The optical fiber display system according to the present invention includes a plurality of core wire identification terminals 101.

Abstract: An optical instrument for determining a wavelength of light generated by a light source. The optical instrument may include a signal generator for generating a driving signal, a tunable optical filter device configured to receive the driving signal, the tunable optical filter device configured to diffract the light generated by the light source based on the driving signal, an optical detector device configured to detect a timing of maximum diffraction of light diffracted by the tunable optical filter device, and an analyzer configured to determine the wavelength of the light based the timing of maximum diffraction.

Abstract: Examples described herein relate to an optical system. In some examples, the optical system may include a light-conducting medium and a first optical device to transmit an optical signal over the light-conducting medium. Further, the optical system may include a second optical device coupled to the light-conducting medium to receive an optical signal transmitted by the first optical device. In some examples, at least one of the first optical device, the light-conducting medium, and the second optical device may include an in-situ capacitive structure to detect light intensity. Moreover, the optical system may include a monitoring circuit electrically coupled to the in-situ capacitive structure to generate an electrical signal indicative of the light intensity detected by the in-situ capacitive structure.

Abstract: Embodiments of the invention include an active fiber with a piezoelectric layer that has a crystallization temperature that is greater than a melt or draw temperature of the fiber and methods of forming such active fibers. According to an embodiment, a first electrode is formed over an outer surface of a fiber. Embodiments may then include depositing a first amorphous piezoelectric layer over the first electrode. Thereafter, the first amorphous piezoelectric layer may be crystallized with a pulsed laser annealing process to form a first crystallized piezoelectric layer. In an embodiment, the pulsed laser annealing process may include exposing the first amorphous piezoelectric layer to radiation from an excimer laser with an energy density between approximately 10 and 100 mJ/cm2 and pulse width between approximately 10 and 50 nanoseconds. Embodiments may also include forming a second electrode over an outer surface of the crystallized piezoelectric layer.

Abstract: A configurable passive mixer is described herein. According to one exemplary embodiment, a passive mixer for a wireless receiver comprises a plurality of passive mixer cores coupled in parallel with each mixer core configured to receive a same set of radio frequency input signals and a separately driven set of local oscillator input signals. Further, each mixer core is configured to be separately enabled or disabled so that the passive mixer can be selectively configured during operation to convert the same set of radio frequency input signals to a set of downconverted output signals that satisfy a certain performance requirement or performance parameter of the passive mixer.

Abstract: Structures for a polarizer and methods of forming a structure for a polarizer. A polarizer includes a first waveguide core and a layer that is positioned adjacent to a side surface of the first waveguide core. The layer is composed of a first material having a permittivity with an imaginary part that ranges from 0 to about 15. A second waveguide core is positioned over the first waveguide core. The second waveguide core is composed of a second material that is different in composition from the first material.

Abstract: A light-scanning endoscope is provided with: a light-scanner that causes an optical fiber to be vibrated; a controller that causes light to be emitted from the optical fiber with the same phase as the vibrations; an adjusting unit that adjusts a distortion correction amount on the basis of a shape of a row of irradiation positions of the light on an imaging subject; and a phase correcting unit that corrects the phase in which the light is emitted on the basis of the adjusted distortion correction amount.

Abstract: An infrared imaging apparatus having thin film spatial filters in a stacked array to filter and collate light generated internally by the infrared imaging apparatus such that the light generated impacts a detection area of the imaging apparatus at or near a critical angle. The index of refraction of the detection area being subject to change when irradiated with infrared light such that the amount of light generated internally and reflected to a light detector attached to the imaging apparatus varies with the intensity of the irradiating infrared light.

Abstract: A silicon photonic device is provided including a substrate; a passive silicon optical device, on the substrate; an electrically insulating cladding layer that encapsulates the optical device on the substrate, the cladding layer including a trench patterned therein, so as for the trench to at least partly cover the optical device, on a side of the latter, the trench filled with an electrically insulating, thermally conducting material, having a refractive index that is lower than a refractive index of silicon, thereby forming a heat conduction channel toward the optical device; and a heating element, in contact with the thermally conducting material. A method of operating such silicon photonic devices is also provided.

Abstract: A hollow-core photonic crystal fiber (HC-PCF) assembly for converting input radiation to broadband radiation, the hollow core fiber assembly including: a micro-structured fiber with a hollow core extending along a length of the fiber from an input end configured to receive input radiation to an output end configured to output broadband radiation, wherein the hollow core of the fiber is configured to include a medium; and a density control system configured to control a density profile of the medium along at least a part of the length of the fiber to establish a desired zero dispersion wavelength profile along at least a part of the length of the fiber.

Abstract: An optical device includes an optical modulator formed on an optical IC chip. A shape of the IC chip is a rectangle or a parallelogram. The optical modulator includes an interferometer, wiring patterns, a first polymer pattern, and a second polymer pattern. The interferometer includes an optical waveguide that is formed in a direction from a first edge to a second edge of the optical IC chip. The wiring patterns are formed parallel to the optical waveguide. The first polymer pattern is formed along the first edge or the second edge. The second polymer pattern is connected to the first polymer pattern and formed on the optical waveguide without overlapping the wiring patterns.

Abstract: A system and a method for generating tunable ultrafast optical pulses, the method comprising spectral broadening of a laser input beam by propagating the laser input beam in a nonlinear medium of a third-order nonlinear susceptibility ?(3), yielding an output laser spectrum; and one of: i) selecting at least one portion of the output laser spectrum, yielding an output pulse different than the input pulse and centered at a different frequency; ii) temporal compensation and spatial spreading of spectral components of the output laser spectrum; selecting two pulses at two different frequencies; and nonlinearly mixing the two pulses together in a first second-order nonlinear susceptibility ?(2) nonlinear crystal into a third pulse centered at a frequency which is a difference between the frequencies of the first two pulses; and iii) dividing output laser spectrum into a pump beam and a probe beam, directing a pump pulse to a third second-order nonlinear crystal for THz radiation generation; and directing a probe

Abstract: To provide a multiplexer that makes it possible to achieve a reduction in size and that minimizes the influence of the expansion of laser light on a multiplexing unit. A multiplexer is provided with a plurality of waveguides, multiplexing units that are provided at an intermediate location within the waveguides, and laser light sources, wherein: the first multiplexing unit is arranged at a position that is closest to the laser light sources; and the laser light sources that have an optical axis at a position that is separated from the transmission axis of the visible light that is introduced into the first multiplexing unit are arranged so that the optical axis is inclined with respect to the transmission axis and the outer periphery of laser light that expands at a predetermined expansion angle passes in front of the first multiplexing unit.

Abstract: An interposer (16) and a substrate (10) incorporating the interposer (16) are provided. The interposer (16) includes one or more layers (18) and a cavity (20) defined in the one or more layers (18), the cavity (20) being configured as a waveguide for propagation of electromagnetic waves.

Abstract: An optical transmission system includes an optical transmitter configured to generate a plurality of optical signals encoded and modulated with the same client data being carriers with the same wavelength, and having different carrier phases, and output the plurality of generated optical signals using a plurality of optical transmitter output ports, each of the optical transmitter output ports corresponding to one of the plurality of optical signals, and one or a plurality of first directional couplers including a plurality of first input ports, each of the first input port connected to a corresponding one of the plurality of optical transmitter output ports.

Abstract: A radiation source includes: a hollow core optical fiber, a working medium; and a pulsed pump radiation source. The hollow core optical fiber has a body and has a hollow core. The working medium is disposed within the hollow core. The pulsed pump radiation source is arranged to produce pulsed pump radiation that is received by, and propagates through, the hollow core from an input end to an output end. One or more parameters of the pulsed pump radiation, the optical fiber and the working medium are configured to allow soliton self-compression of the pulsed pump radiation so as to change a spectrum of the pulsed pump radiation so as to form output radiation. In some embodiments, a length of the optical fiber is such that the output end substantially coincides with a position at which a temporal extent of the pulsed pump radiation is minimal.

Abstract: A method of manufacturing a nanoelectromechanical resonator allows for uniform tuning of a resonant frequency. The nanoelectromechanical resonator can be mass produced and used to sense the presence of a selected gas.

Abstract: A digital-to-analog converter has a first interface coupled to a second interface through one or more modulation circuits. The circuits include a first coupler connected to the first interface; a first waveguide with a first lead connected to the first coupler, a first end, and a first length running therebetween. The first lead and the first end are coupled by a first switch. The circuits also include: a second coupler connected to the first interface; a second waveguide having a second lead connected to the second coupler, a second end, and a second length running therebetween, the second lead and the second end coupled by a second switch along the second length; and an optical combiner connected to the ends of the waveguides. The second interface is connected to the optical combiner of the modulation circuits. Output from the second interface is an optical signal capable of carrying binary information.

Abstract: A semiconductor optical integrated device according to the present invention includes a conductive substrate, a laser provided to the conductive substrate, a semi-insulating semiconductor layer provided on the conductive substrate, a photodiode provided on the semi-insulating semiconductor layer and a waveguide that is provided on the conductive substrate and guides output light of the laser to the photodiode, wherein an anode of the photodiode and a cathode of the photodiode are drawn from an upper surface side of the photodiode, and the waveguide and the photodiode are separated from each other by the semi-insulating semiconductor layer.

Abstract: An optoelectronic device, including: a rib waveguide, the rib waveguide including: a ridge portion, which includes a temperature-sensitive optically active region, and a slab portion, positioned adjacent to the ridge portion; the device further comprising a heater, disposed on top of the slab portion wherein a part of the heater closest to ridge portion is at least 2 ?m away from the ridge portion. The device may also have a heater provided with a bottom cladding layer, and may also include various thermal insulation enhancing cavities.

Abstract: Techniques for producing a Brillouin laser are provided. According to some aspects, techniques are based on forward Brillouin scattering and a multimode acousto-optic waveguide in which light is scattered between optical modes of the waveguide via the Brillouin scattering. This process may transfer energy from a waveguide mode of pump light to a waveguide mode of Stokes light. This process may be referred to herein as Stimulated Inter-Modal Brillouin Scattering (SIMS). Since SIMS is based on forward Brillouin scattering, laser (Stokes) light may be output in a different direction than back toward the input pump light, and as such there is no need for a circulator or other non-reciprocal device to protect the pump light as in conventional devices.

Abstract: Two optical waveguides and an insulating film provided to cover the optical waveguides are formed over an insulating layer. Two wirings and a heater metal wire are formed over the insulating film via an insulating film different from the above insulating film. The latter insulating film is thinner than the former insulating film, and has a higher refractive index than the former insulating film. The leaked light from either of the two optical waveguides can be suppressed or prevented from being reflected by any one of the two wirings, the heater metal wire, and the like to travel again toward the two optical waveguides by utilizing the difference between the refractive indices of the two insulating films.

Abstract: The present invention relates to a photonic chip realized by combining at least one Programmable Photonics Analog Block (PPAB) and at least one Reconfigurable Photonic Interconnection (RPI) implemented over a photonic chip that is capable of implementing one or various simultaneous photonics circuits and/or linear multipart transformations by the appropriate programming of its resources (i.e. PPABs and RPIs) and the selection of its input and output ports. The invention also relates to a field-programmable photonic array (FPPA) comprising at least a programmable circuit based on tunable beamsplitters with independent coupling and phase-sifting configuration and peripheral high-performance building blocks.

Abstract: Various waveguides and image display systems are disclosed herein. In an example, an image display system can include an optical engine configured to generate an image and a waveguide. The waveguide can have a light in-coupling region formed along a peripheral edge of the waveguide, the light in-coupling region including a first surface with a first set of diffraction gratings, and a light exit region formed along a top surface of the waveguide, the light exit region including a second set of diffraction gratings. The first set of diffraction gratings can be configured to diffract light towards the second set of diffraction gratings, and the second set of diffraction gratings can be configured to diffract light towards the user's eye.

Abstract: A electronic method, includes receiving, by a graphene structure, a SPP mode of a particular frequency. The electronic method includes receiving, by the graphene structure, a driving microwave voltage. The electronic method includes generating, by the graphene structure, an entanglement between optical and voltage fields.

Abstract: In one embodiment, a module for plugging into a QSFP-DD (Quad Small Form Factor Pluggable Double Density) cage is provided that has one or more projections for contacting a QSFP-DD optical module in an adjacent QSFP-DD recess of the QSFP-DD cage so as to evacuate heat from, and or provide power to, the QSFP-DD optical module.

Abstract: A cascaded modulator system configured to minimize the extinction ratio (ER) of an optical output of an optical transmitter. The cascaded modulator system includes a pulse position modulation (PPM) source connected to a plurality of serially-connected Mach Zehnder Interferometer (MZIs). A variable time delay ?td may be applied to a negative low voltage differential signal (LVDS) driving a second or later MZI of the plurality of MZIs to eliminate or compensate for one or more non-idealities in an electrical signal.

Abstract: A plasmonic phase modulator is provided. The modulator has a conductive layer, and a dielectric layer disposed on the conductive layer. A plasmonic layer is disposed on the dielectric layer. A plasmonic layer is disposed on the dielectric layer. The plasmonic layer is conductive to surface plasmon polariton (SPP) waves. The plasmonic layer may be, for example, a graphene sheet. A voltage signal source is operatively connected between the conductive layer and the plasmonic layer for modulating a propagation speed of an SPP wave propagating on the plasmonic layer.

Abstract: A method for spectral filtering an input optical signal is described. The filtering system uses Brillouin gain inside an interferometer. The interferometer is biased to null signals that propagate without Brillouin gain, but due to asymmetric levels of gain in the interferometer arms the interference null is disturbed for signals of an optical frequency that experience Brillouin gain. The filter thereby preferentially passes signal frequencies that are inside the Brillouin gain bandwidth creating a high extinction ratio filter. The narrow bandwidth of the Brillouin gain effect can allow for spectrally narrow filters such as 30 MHz. The filter can be realized in a stable Sagnac loop configuration even if the pump and signal are combined prior to the Sagnac loop by using a power control device such as an attenuator placed asymmetrically inside the loop. The filter can achieve net gain and can be designed to have a tunable bandwidth.

Abstract: An optical modulator has an optical input port and an optical output port provided on a same end of a substrate; an optical waveguide pair formed in the substrate and configured to form a Mach-Zehnder interferometer, one end of the optical waveguide pair being connected to the optical input port and the other end of the optical waveguide pair being connected to the optical output port, the optical waveguide pair having a bending part; a groove provided along the optical waveguide pair in the bending part; and a signal electrode that applies a high-frequency electrical signal to the optical waveguide pair, wherein the signal electrode has an expanded section having an increased cross sectional area at a section intersecting the groove.

Abstract: Provided is a driving device for PWM control of voltage pulses for controlling the temperature of a heater in a phase controller, the driving device being capable of increasing the response speed of an optical element such as an optical switch. Phase controllers include first and second heaters for changing the temperatures of first and second optical waveguides extending in parallel. Driving devices include pulse generation circuits that generate voltage pulses to apply to the first and second heaters. To start raising the temperature of the second heater, the pulse generation circuit generates a first voltage pulse and consecutive second voltage pulses to apply to the second heater with zero voltage pulse being applied to the first heater, the first voltage pulse having a long pulse width and the second voltage pulses following the first voltage pulse and having a shorter pulse width than the first voltage pulse.

Abstract: Methods and apparatus for providing all-optically generated, on-chip propagated and high-efficiency tunable plasmons are described. The plasmon generating apparatus includes a graphene based silicon nitride waveguide (GSiNW) utilizing ‘C+L’ band light sources and detectors that take advantage of the surface 2nd nonlinearity on graphene. The optical generation is accomplished via one or more optical communication lasers through the difference-frequency generation process. The THz frequency and intensity is tunable via an external gate voltage. Using such a device the optical to THz conversion may be made at least an order of magnitude more efficient than prior THz sources, and can be used to make chip-scale room-temperature THz sources, switches, modulators and detectors based on graphene.

Abstract: A semiconductor device includes an insulating layer, an optical waveguide formed on the insulating layer, a multilayer wiring layer formed on the insulating layer such that the multilayer wiring layer covers the optical waveguide, and a first inductor formed in the multilayer wiring layer.

Abstract: A Faraday-based polarization scrambler is disclosed. The Faraday-based polarization scrambler may comprise a first toroidal assembly. The first toroidal assembly may include an optical fiber that is looped to form a first looped portion, and a first electrical wire that coils around the first looped portion to form a first toroidal configuration. In some examples, the first electrical wire may be connected to a voltage source and carries a current to form a magnetic field within the first toroidal configuration. In some examples, there may be additional toroidal assemblies provided to the Faraday-based polarization scrambler. One or more of these toroidal assemblies may create an actuation field to effect modulation for polarization scrambling and emulation that mitigates polarization-dependent effects.

Abstract: An actuator includes an actuator substrate and a diaphragm forming an inner wall defining a space in the actuator substrate. The diaphragm includes a first layer made of material that does not transmit light of a specific wavelength; a second layer made of material that transmits the light of a specific wavelength; an active region covering a central area of the diaphragm, the active region including the first layer and the second layer; and at least two transmissive regions formed at a circumference of the diaphragm, each of the at least two transmissive regions including the second layer without the first layer.

Abstract: The invention relates to an electrooptical device comprising a semiconductor substrate having a front side and a back side, at least one photonic component arranged on the front side of the semiconductor substrate, the photonic component comprising an active layer made of a non-linear optical material, wherein at least one cavity, extends through the semiconductor substrate and connects the active layer on the front side of the semiconductor substrate with the back side of the semiconductor substrate.

Abstract: An apparatus for mitigating polarization dependent loss (PDL) in an optical signal-to-noise ratio (OSNR) of a modulated optical signal is disclosed. The apparatus may comprise a spectrum analyzer to measure an optical power spectrum of a modulated optical signal. The apparatus may also comprise a measuring unit to select a first portion of the modulated optical signal and a second portion of the modulated optical signal, where each of the first and second portions of the modulated optical signals may include an independent noise distribution indicative of PDL, and measure a time-varying parameter of the first and second portions. The apparatus may also include a signal processor to PDL in an OSNR by transforming any elliptical polarization associated with the independent noise distribution into a ball polarization, determining a correlation between time-varying parameters of the first and second portions, and calculating a PDL mitigated OSNR.

Abstract: An optical modulator includes an optical modulation element having a plurality of signal electrodes; a plurality of signal input terminals each of which inputs an electrical signal to be applied to each signal electrode; a relay substrate on which a plurality of signal conductor patterns electrically connecting the signal input terminals and the signal electrodes, and a plurality of ground conductor patterns are formed; and a housing that houses the optical modulation element and the relay substrate, in which the relay substrate has at least one groove extending from the signal input side on which the signal input terminal is connected to the signal conductor pattern, in at least one ground conductor pattern formed between adjacent signal conductor patterns, and the groove is formed such that a length extending from the signal input side is longer than a length of the signal input terminal extending on the signal conductor pattern.

Abstract: This disclosure provides systems, methods, and apparatus related to optical modulators. In one aspect, a device includes a substrate, a first electrically insulating material disposed over the substrate, a first graphene layer and a second graphene layer disposed in the first electrically insulating material and being separated by the first electrically insulating material, and a waveguide disposed on the first electrically insulating material. At least a portion of the second graphene layer overlays at least a portion of the first graphene layer. The waveguide overlays both the first graphene layer and the second graphene layer.

Abstract: An optoelectronic component includes a chip having a substrate and at least one optical waveguide integrated in the chip. The electro-optical component may be monolithically integrated in one or a plurality of semiconductor layers of the chip arranged on the substrate top side of the substrate, or on the substrate top side of the substrate. At least one electrical connection of the monolithically integrated electro-optical component is connected by means of a connection line to a conductor track connection situated below the substrate rear side. The connection line extends through a hole in the substrate from the electro-optical component to the conductor track connection situated below the substrate rear side.

Abstract: A method for fabricating a photonic integrated circuit (PIC) comprises providing a silicon-on-insulator (SOI) wafer comprising an insulator layer disposed between a base semiconductor layer and a SOI layer, wherein the SOI layer comprises a waveguide, providing at least one slot within the SOI layer, wherein the at least one slot is positioned on the same or opposite sides of the waveguide, and wherein the at least one slot is positioned at a predetermined distance away from the waveguide, and removing a portion of the insulator layer to form an etched-out portion of the insulator layer, wherein the etched-out portion is positioned directly beneath the waveguide, and wherein a width of the etched-out portion is at least the width of the waveguide.

Abstract: The present disclosure relates to semiconductor structures and, more particularly, to through-silicon vias (TSV) for heterogeneous integration of semiconductor device structures and methods of manufacture. The structure includes: a plurality of cavity structures provided in a single substrate; at least one optical device provided on two sides of the single substrate and between the plurality of cavity structures; and a through wafer optical via extending through the substrate, between the plurality of cavity structures and which exposes a backside of the at least one optical device.

Abstract: An optical device may include a waveguide-based Mach-Zehnder (MZ) interferometer associated with performing polarization multiplexing or demultiplexing. The waveguide-based MZ interferomenter may include a first MZ arm, a second MZ arm, and a set of stress-balancing trenches. A portion of the first MZ arm may be between at least two stress-reducing trenches of a plurality of stress-reducing trenches. The plurality of stress-reducing trenches may be in a cladding layer on a substrate. The set of stress-balancing trenches may be on an opposite side of the second MZ arm from the plurality of stress-reducing trenches. The set of stress-balancing trenches may be in the cladding layer on the substrate.

Abstract: An optical scanning method includes detecting a resonance frequency of a tip of a fiber while sweeping a vibration frequency of the tip of the fiber over a predetermined frequency range, the tip of the fiber being supported to allow oscillation, determining a driving frequency of the tip of the fiber on the basis of the detected resonance frequency, and scanning light over an object by causing the light to be emitted from the tip of the fiber while driving and vibrating the tip of the fiber at the driving frequency.

Abstract: An optical control element including an optical waveguide formed by using diffusion of titanium that is formed on a lithium niobate substrate and a control electrode formed on the lithium niobate substrate that is provided in the vicinity of the optical waveguide, in which an amount of a hydroxyl group absorbed into the lithium niobate substrate is set to be in a range of 0.5 to 2.5 cm?1.

Abstract: A system is provided for use with an optical input signal for detecting a phase difference between a first RF signal having a first phase and a second RF signal having a second phase. The system includes and optical waveguide, a first optical resonant cavity, a first RF receiver, a second optical resonant cavity and a second RF receiver. The optical resonant cavities include a non-linear electro-optical material. The first RF receiver affects the first non-linear electro-optical material of the first optical resonant cavity. The second RF receiver affects the second non-linear electro-optical material of first optical resonant cavity. The optical waveguide outputs an optical output signal based on the optical input signal as modified by the first optical resonant cavity as affected by the first RF receiver receiving the first RF signal and as modified by the second optical resonant cavity as affected by the second RF receiver.

Abstract: To provide a highly-reliable low-cost small optical modulator in which temperature drift is suppressed and an optical transmission device using the same. An optical modulator including an optical waveguide substrate 1 on which an optical waveguide is formed, a signal electrode which is provided on the optical waveguide substrate and applies an electric field to the optical waveguide, a termination substrate 3 provided with a termination resistor that terminates the signal electrode, and a housing 6 in which the optical waveguide substrate and the termination substrate are mounted, in which, in order to suppress conduction of heat generated from the termination resistor to the optical waveguide substrate through the housing, a groove 8 is formed in the housing 6 between the termination substrate 3 and the optical waveguide substrate 1.