Structures described herein may include mechanically bonded interlayers for formation between a first Group III-V semiconductor layer and a second semiconductor layer. The mechanically bonded interlayers provide reduced lattice strain by strain balancing between the Group III-V semiconductor layer and the second semiconductor layer, which may be silicon.

Core-cladding planar waveguide (PWG) structures and methods of making and using same. The core-cladding PWG structures can be synthesized by hydride vapor phase epitaxy and processed by mechanical and chemical-mechanical polishing. An Er doping concentration of [Er] between 1×10.sup.18 atoms/cm.sup.3 and 1×10.sup.22 atoms/cm.sup.3 can be in the core layer. Such PWGs have a core region that can achieve optical confinement between 96% and 99% and above.

A method and a laser for breaking through the limitation of fluorescence spectrum on laser wavelength is disclosed. The method includes: exciting electrons to a high energy level by pump light, and suppressing an oscillation of radiation light by laser cavity coating, using a laser resonance to enhance a transition probability of an electron-phonon coupling from the high energy level to a multi-phonon coupling level, so as to realize the emission and enhancement of breakthrough fluorescence spectrum and realize the radiation light oscillation, wherein the laser cavity includes an incident mirror, a folding mirror, a tuning element and an exit mirror arranged in sequence along an optical path direction, the laser gain medium is located between an incident mirror and a folding mirror in the laser resonator, and the tuning element is arranged in the laser cavity at a Brewster angle.

A single-frequency laser apparatus comprises a mirror and a volume Bragg grating (VBG) reflector defining a laser cavity therebetween and an optical gain material for emitting and amplifying an intra-cavity beam in the laser cavity. The optical gain material comprises a transition-metal doped crystal such as a crystal doped with transition-metal ions selected from one or more of Ti.sup.3+ ions, Cr.sup.2+ ions, Cr.sup.3+ ions or Cr.sup.4+ ions. A reflectivity spectrum of the VBG reflector and an optical length of the laser cavity are selected so that a beam output from the laser cavity is a single-frequency output beam and/or includes only one longitudinal mode of the laser cavity. The laser apparatus may provide a robust, compact, low cost, high-power wavelength adjustable (from approximately 650 to 950 nm), narrow linewidth (<100 kHz), single frequency laser source which is suitable for a wide range of applications from laser sensing, spectroscopy, and high precision frequency metrology sectors.

A single-mode micro-laser based on a single whispering gallery mode optical microcavity and a preparation method thereof described includes: preparing a desired single whispering gallery mode optical microcavity doped with rare earth ions or containing a gain material such as quantum dots, wherein an optical microcavity configuration include a micro-disk cavity, a ring-shaped microcavity, and a racetrack-shaped microcavity; a material type include lithium niobate, silicon dioxide, silicon nitride, etc.; preparing an optical fiber cone or an optical waveguide of a required size which can excite high-order modes of the optical microcavity, such as a ridge waveguide and a circular waveguides; and coupling, integrating, and packaging the optical fiber cone or the optical waveguide with the microcavity. A pump light is coupled to the optical fiber cone or the optical waveguide to excite a compound mode with a polygonal configuration.

Hybrid silicon devices are disclosed in which a silicon-based resonant structure is coated with a rare-earth-doped tellurium oxide layer that facilitates optical gain, thereby forming a silicon-based laser cavity. The silicon-based laser cavity supports at least one resonant mode that has a modal volume extending from the silicon resonant base structure into the rare-earth-doped tellurium oxide layer. The silicon-based laser cavity is optically coupled to a silicon waveguide to facilitate the delivery of pump laser energy to the silicon-based laser cavity, such that at least a portion of the pump laser energy propagating through the silicon waveguide is coupled to the silicon-based laser cavity for excitation of the rare earth dopant within the rare-earth-doped tellurium oxide layer. The silicon waveguide that is optically coupled to the silicon-based laser cavity also facilitates the external delivery of the laser energy generated within silicon-based laser cavity.

There are provided a first cladding layer formed on a Si substrate, a first core made of Si and formed on the first cladding layer, and a second cladding layer formed on the first cladding layer and covering the first core Additionally, this optical device includes a waveguide type laser formed over the second cladding layer, a second core made of InP and formed continuously to the laser, and a third cladding layer formed on the second cladding layer and covering the laser and the second core.

Systems and methods described herein may include a first semiconductor layer with a first lattice constant, a rare earth pnictide buffer epitaxially grown over the first semiconductor, wherein a first region of the rare earth pnictide buffer adjacent to the first semiconductor has a net strain that is less than 1%, a second semiconductor layer epitaxially grown over the rare earth pnictide buffer, wherein a second region of the rare earth pnictide buffer adjacent to the second semiconductor has a net strain that is a desired strain, and wherein the rare earth pnictide buffer may comprise one or more rare earth elements and one or more Group V elements. In some examples, the desired strain is approximately zero.

An intra-cavity doubled OPS-laser has a laser-resonator including a birefringent filter (BRF) for coarse wavelength-selection, and an optically nonlinear (ONL) crystal arranged for type-II frequency-doubling and fine wavelength-selection. Laser-radiation circulates in the laser-resonator at one of a range of fundamental wavelengths dependent on the resonator length. The ONL crystal has a transmission peak-wavelength dependent on the crystal temperature. Reflection of circulating radiation from the BRF is monitored. The reflection is at a minimum when the ONL crystal transmission-peak wavelength is at the circulating radiation wavelength. The temperature of the ONL crystal is selectively varied to maintain the monitored reflection at about a minimum.

A multiple frequency comb source apparatus (100) for simultaneously creating a first laser pulse sequence representing a first frequency comb (1) and at least one further laser pulse sequence representing at least one further frequency comb (2), wherein at least two of the first and at least one further pulse sequences have different repetition frequencies, comprises a laser resonator device (10) comprising multiple resonator mirrors including first end mirrors EM.sub.1,OC.sub.1 providing a first laser resonator (11), a laser gain medium (21, 22) being arranged in the laser resonator device (10), and a pump device (30) being arranged for pumping the laser gain medium (21), wherein the laser resonator device (10) is configured for creating the first and at least one further laser pulse sequences by pumping and passively mode-locking the laser gain medium (21), the resonator minors of the laser resonator device (10) include further end minors EM.sub.2, OC.sub.2 providing at least one further laser resonator (12), the first laser resonator (11) and the at least one further laser resonator (12) share the laser gain medium (21), resonator modes of the first laser resonator (11) and the at least one further laser resonator (12) are displaced relative to each other, wherein the resonator modes are located in the laser gain medium (21) at separate beam path spots, and at least one of the first and further end minors EM.sub.1, EM.sub.2, OC.sub.1, OC.sub.2 is adjustable so that the repetition frequency of at least one of the first and at least one further laser pulse sequences can be set independently from the repetition frequency of the other one of the first and at least one further laser pulse sequences. Furthermore, a spectroscopic measuring method, a spectroscopy apparatus and a multiple frequency comb generation method are described.