Abstract: A wavelength tunable laser includes: a heating layer, a dielectric layer, reflectors, a transport layer, a support layer, and a substrate layer. The heating layer is located above the transport layer; the transport layer is located above the support layer, and the transport layer includes an upper cladding layer, a waveguide layer, and a lower cladding layer from top to bottom; the reflector is located in the transport layer; the support layer has a protection structure, where the protection structure forms a hollow structure together with the transport layer and the substrate layer, and the hollow structure has a support structure; and the substrate layer is located below the support layer. The heating layer, the reflector, and a part of the transport layer form a suspended structure to prevent heat dissipation. Thus thermal tuning efficiency can be improved, and power consumption can be lowered.

Abstract: A metal-oxide semiconductor (MOS) optical modulator including a doped semiconductor layer having a waveguide structure, a dielectric layer disposed over the waveguide structure of the doped semiconductor layer, a gate region disposed over the dielectric layer, wherein the gate region comprises a transparent electrically conductive material having a refractive index lower than that of silicon, and a metal contact disposed over the gate region. The metal contact, the gate region, and the waveguide structure of the doped semiconductor layer may be vertically aligned with each other.

Abstract: A tunable laser is provided, including a first reflector, a second reflector, a phase adjustment area, a gain area, a first detector, a second detector, and a controller. The phase adjustment area is located between the first reflector and the gain area, the gain area is located between the phase adjustment area and the second reflector, a reflectivity of the first reflector is adjustable, and a reflectivity of the second reflector is adjustable. The first detector is configured to convert an optical signal of the first reflector into a first electrical signal. The second detector is configured to convert an optical signal of the second reflector into a second electrical signal. The controller is configured to adjust at least one of the reflectivity of the first reflector or the reflectivity of the second reflector based on the first electrical signal and the second electrical signal.

Abstract: A PAM4 signal generation apparatus is provided. The PAM4 signal generation apparatus includes a DFB, two EA modulators, an SOA, a PSR, a direct-current power source, two electrical-signal generators, and two amplitude-limiting amplifiers. The two electrical-signal generators and the two amplitude-limiting amplifiers are used to generate two NRZ electrical signals respectively, the DFB outputs two optical signals, the SOA amplifies an optical power of one of the optical signals, the two EA modulators use the NRZ electrical signals and the optical signals including “a large signal and a small signal” respectively to generate two NRZ optical signals respectively, and the two NRZ optical signals are multiplexed by the PSR to generate a PAM4 electrical signal. According to this apparatus, a linearity requirement is greatly lowered. PAM4 modulation is performed in an optical domain, and this prevents a PAM4 signal from being generated on an electrical signal.

Abstract: An apparatus comprises: a first input tap; a first optical modulator coupled to the first input tap; a first output tap coupled to the first optical modulator so that the first optical modulator is positioned between the first input tap and the first output tap; and a controller indirectly coupled to the first input tap and the first output tap.

Abstract: A PAM4 signal generation apparatus is provided. The PAM4 signal generation apparatus includes a DFB, two EA modulators, an SOA, a PSR, a direct-current power source, two electrical-signal generators, and two amplitude-limiting amplifiers. The two electrical-signal generators and the two amplitude-limiting amplifiers are used to generate two NRZ electrical signals respectively, the DFB outputs two optical signals, the SOA amplifies an optical power of one of the optical signals, the two EA modulators use the NRZ electrical signals and the optical signals including “a large signal and a small signal” respectively to generate two NRZ optical signals respectively, and the two NRZ optical signals are multiplexed by the PSR to generate a PAM4 electrical signal. According to this apparatus, a linearity requirement is greatly lowered. PAM4 modulation is performed in an optical domain, and this prevents a PAM4 signal from being generated on an electrical signal.

Abstract: Embodiments of the present disclosure relate to a surface-mount laser apparatus. One example apparatus includes an on-chip laser, a passive waveguide, and a waveguide detector. The waveguide detector includes a first ridge waveguide. The on-chip laser includes a second ridge waveguide. The on-chip laser is coupled with the passive waveguide by the second ridge waveguide, and the waveguide detector is coupled with the passive waveguide by the first ridge waveguide.

Abstract: A method for fabricating a photonic integrated circuit (PIC) comprises providing a wafer comprising an insulator layer positioned between a top semiconductor layer and a base semiconductor layer, patterning the top semiconductor layer to simultaneously define a waveguide and a first etch mask window for forming a fiber-guiding v-groove that substantially aligns to an axis of optical signal propagation of the waveguide, removing a first portion of the top semiconductor layer to form the waveguide according to the patterning, removing a second portion of the top semiconductor layer to form the first etch mask window according to the patterning, and forming the fiber-guiding v-groove according to the first etch mask window.

Abstract: A metal-oxide-semiconductor (MOS) type semiconductor device, comprising a silicon substrate, a first cathode electrode and a second cathode electrode coupled to the silicon substrate and located on distal ends of the silicon substrate, a poly-silicon (Poly-Si) gate proximally located above the silicon substrate and between the first cathode electrode and the second cathode electrode, wherein the Poly-Si gate comprises a first post extending orthogonally relative to the silicon substrate comprising a first doped silicon slab, a second post extending orthogonally relative to the silicon substrate comprising a second doped silicon slab, wherein the second post is positioned so as to create a width between the first post and the second post, an anode electrode coupled to the first post and the second post and extending laterally from the first post to the second post, and a dielectric layer disposed between the first silicon substrate and the second silicon substrate.

Abstract: A method for fabricating a photonic integrated circuit (PIC) comprises providing a wafer comprising an insulator layer positioned between a top semiconductor layer and a base semiconductor layer, patterning the top semiconductor layer to simultaneously define a waveguide and a first etch mask window for forming a fiber-guiding v-groove that substantially aligns to an axis of optical signal propagation of the waveguide, removing a first portion of the top semiconductor layer to form the waveguide according to the patterning, removing a second portion of the top semiconductor layer to form the first etch mask window according to the patterning, and forming the fiber-guiding v-groove according to the first etch mask window.

Abstract: An apparatus comprises: a first input tap; a first optical modulator coupled to the first input tap; a first output tap coupled to the first optical modulator so that the first optical modulator is positioned between the first input tap and the first output tap; and a controller indirectly coupled to the first input tap and the first output tap.

Abstract: An edge coupling device including a substrate, a buried oxide disposed over the substrate, a cladding material disposed over the buried oxide, where the cladding material includes a trench, an inversely tapered silicon waveguide disposed within the cladding material beneath the trench, and a ridge waveguide disposed within the trench, where the ridge waveguide and the inversely tapered silicon waveguide are vertically-aligned with each other.

Abstract: Nanoparticles described as metal-encapsulated carbonaceous dots or M@C-dots are disclosed. Also disclosed are specific M@C-dots with gadolinium, so called Gd@C-dots. These nanoparticles are biologically inert and preclude the release of metal in biological environments. In addition, despite a dimension exceeding the commonly recognized threshold for renal clearance, the disclosed nanoparticles can be efficiently cleared via urine after systematic injection. Methods of making and using such nanoparticles are also disclosed.

Abstract: Photodynamic therapy systems comprising a nanoparticle that emits electromagnetic radiation having a first wavelength when irradiated with electromagnetic radiation, a photosensitizer which absorbs electromagnetic radiation of said first wavelength and a biocompatible mesoporous material are disclosed herein. In some examples, the photodynamic therapy system comprises a core comprising the nanoparticle, a first shell comprising the biocompatible mesoporous material, and a photosensitizer embedded in the first shell. Upon irradiation by, for example, X-rays, the nanoparticle can function as a transducer, converting X-ray photons to visible photons, and in turn, activating the photosensitizers. Methods of using the photodynamic therapy system are also disclosed.

Abstract: A method of fabricating an edge coupling device and an edge coupling device are provided. The method includes removing a portion of cladding material to form a trench over an inversely tapered silicon waveguide, depositing a material having a refractive index greater than silicon dioxide over remaining portions of the cladding material and in the trench, and removing a portion of the material within the trench to form a ridge waveguide.

Abstract: Gd-encapsulated carbonaceous dots (Gd@C-dots) hold great potential in clinical translation as Ti contrast agent for magnetic resonance imaging. However, current synthetic techniques yield particles with poor size control; hence, time-consuming size selection is often needed to obtain particles of desired sizes. Disclosed is a process whereby mesoporous silica nanoparticles are used as templates for size-controlled synthesis of Gd@C-dots. The disclosed methods involve calcining a mixture comprising a mesoporous silica nanoparticle, a gadolinium-containing compound, and a chelator, thereby forming the nanoparticles of gadolinium within the mesoporous silica nanoparticle; and removing the mesoporous silica nanoparticle from the nanoparticles of gadolinium.

Abstract: A monolithically integrated thermal tunable laser comprising a layered substrate comprising an upper surface and a lower surface, and a thermal tuning assembly comprising a heating element positioned on the upper surface, a waveguide layer positioned between the upper surface and the lower surface, and a thermal insulation layer positioned between the waveguide layer and the lower surface, wherein the thermal insulation layer is at least partially etched out of an Indium Phosphide (InP) sacrificial layer, and wherein the thermal insulation layer is positioned between Indium Gallium Arsenide (InGaAs) etch stop layers.

Abstract: A metal-oxide-semiconductor (MOS) type semiconductor device, comprising a silicon substrate, a first cathode electrode and a second cathode electrode coupled to the silicon substrate and located on distal ends of the silicon substrate, a poly-silicon (Poly-Si) gate proximally located above the silicon substrate and between the first cathode electrode and the second cathode electrode, wherein the Poly-Si gate comprises a first post extending orthogonally relative to the silicon substrate comprising a first doped silicon slab, a second post extending orthogonally relative to the silicon substrate comprising a second doped silicon slab, wherein the second post is positioned so as to create a width between the first post and the second post, an anode electrode coupled to the first post and the second post and extending laterally from the first post to the second post, and a dielectric layer disposed between the first silicon substrate and the second silicon substrate.

Abstract: An apparatus comprising a thick waveguide comprising a first adiabatic tapering from a first location to a second location, wherein the first adiabatic tapering is wider at the first location than at the second location, and a thin slab waveguide comprising a second adiabatic tapering from the first location to the second location, wherein the second adiabatic tapering is wider at the second location than at the first location, and a third adiabatic tapering from the second location to a third location, wherein the third adiabatic tapering is wider at the second location than at the third location, wherein at least a portion of the first adiabatic tapering is adjacent to the second adiabatic tapering, and wherein the first adiabatic tapering and the second adiabatic tapering are separated from each other by a constant gap.

Abstract: A laser comprises a gain medium, and a mirror coupled to the gain medium and comprising a coupler coupled to the gain medium, a phase section coupled to the coupler, a bandpass filter coupled to the phase section, and a comb reflector (CR) coupled to the bandpass filter. A laser chip package comprises a substrate, and a laser coupled to the substrate and comprising a filter comprising a first interferometer with a first transmittance, and a second interferometer with a second transmittance, wherein the filter is configured to provide a filter transmittance based on the first transmittance and the second transmittance, and a comb reflector (CR) coupled to the filter and comprising a ring with a circumference, and a refractive index, wherein the CR is configured to provide a CR reflectivity based on the circumference and the refractive index.