Abstract: A group III-nitride semiconductor device comprises a light emitting semiconductor structure comprising a p-type layer and an n-type layer operable as a light emitting diode or laser. On top of the p-type layer there is arranged an n+ or n++-type layer of a group III-nitride, which is transparent to the light emitted from the underlying semiconductor structure and of sufficiently high electrical conductivity to provide lateral spreading of injection current for the light-emitting semiconductor structure.

Abstract: A depolarizer for a broadband optical source to split the source beam by power, not by polarization state, and route the components into respective light paths. A polarization rotator arranged in one of the light paths rotates the polarization state of that beam component to make it orthogonal to that of the other. The components are then recombined by a combiner and output. A variable optical attenuator is arranged in one of the light paths, which during operation is adjusted by a controller to maintain power equalization between the light paths and hence depolarization performance. The controller receives power measurements from the light paths and from after the combiner via respective sensors. With this feedforward design reminiscent of a Mach-Zehnder interferometer the light from a light source which generates highly polarized light can be depolarized in theory with zero insertion loss and in practice with losses of about 1 dB.

Abstract: A low power, side-emitting semiconductor laser diode is provided. The laser diode is formed from a semiconductor heterostructure having an active layer sandwiched between an n-type layer and a p-type layer, wherein the active layer forms a gain medium of width W. Front and back reflectors of reflectivity Rf and Rb are arranged on opposing side facets of the semiconductor heterostructure part to form a cavity of length L containing at least a part of the active layer which thus forms the gain medium for the laser diode, the gain medium having an internal loss ?i. To achieve stable, low power operation close to threshold, the laser diode is configured with the following parameter combination: width W: 1 ?m?W?2 ?m; cavity length L: 100 ?m?L?600 ?m; internal loss ?i: 0 cm?1??i?30 cm?1; back reflectivity Rb: 100?Rb?80%; and front reflectivity Rf: 100?Rf?60%.

Abstract: A low power, side-emitting semiconductor laser diode is provided. The laser diode is formed from a semiconductor heterostructure having an active layer sandwiched between an n-type layer and a p-type layer, wherein the active layer forms a gain medium of width W. Front and back reflectors of reflectivity Rf and Rb are arranged on opposing side facets of the semiconductor heterostructure part to form a cavity of length L containing at least a part of the active layer which thus forms the gain medium for the laser diode, the gain medium having an internal loss ?i. To achieve stable, low power operation close to threshold, the laser diode is configured with the following parameter combination: width W: 1 ?m?W?2 ?m; cavity length L: 100 ?m?L?600 ?m; internal loss ?i: 0 cm?1?i?30 cm?1; back reflectivity Rb: 100?Rb?80%; and front reflectivity Rf: 100?Rf?60%.

Abstract: A group III-nitride semiconductor device comprises a light emitting semiconductor structure comprising a p-type layer and an n-type layer operable as a light emitting diode or laser. On top of the p-type layer there is arranged an n+ or n++-type layer of a group III-nitride, which is transparent to the light emitted from the underlying semiconductor structure and of sufficiently high electrical conductivity to provide lateral spreading of injection current for the light-emitting semiconductor structure.

Abstract: An external cavity semiconductor laser light source comprises includes a semiconductor gain device operable to provide light amplification; a wavelength selection element including a diffraction grating; and light re-directors. The gain device, light re-directors and grating are arranged so that an optical resonator is established for light portions emitted by the gain device and diffracted by the diffraction grating. The resonator is an external cavity laser resonator. The light source is capable of varying an angle of incidence of radiation circulating in the resonator onto wavelength selection element to select a resonator radiation wavelength dependent on the angle of incidence.

Abstract: An optical module includes a light source. The light source can be a swept wavelength light source, and optical module includes a wavemeter. The wavemeter includes a wavemeter tap capable of directing a wavemeter portion of light produced by the light source away from a main beam, a wavelength selective filter arranged to receive the wavemeter portion, a first wavemeter detector arranged to measure a transmitted radiation intensity of radiation transmitted through the filter, and a second wavemeter detector arranged to measure a non-transmitted radiation intensity of radiation not transmitted through but reflected by the filter. In addition, an optical coherence tomography apparatus includes the optical module.

Abstract: An optical module includes a light source. The light source can be a swept wavelength light source, and optical module includes a wavemeter. The wavemeter includes a wavemeter tap capable of directing a wavemeter portion of light produced by the light source away from a main beam, a wavelength selective filter arranged to receive the wavemeter portion, a first wavemeter detector arranged to measure a transmitted radiation intensity of radiation transmitted through the filter, and a second wavemeter detector arranged to measure a non-transmitted radiation intensity of radiation not transmitted through but reflected by the filter. In addition, an optical coherence tomography apparatus includes the optical module.

Abstract: A swept wavelength light source is provided, the light source includes a semiconductor gain device operable to provide amplification, an optical retarding device, the retarding device having a block of material, a beam path with a well-defined beam path length being defined for light within the block of material produced by the gain device, a wavelength selector, and the gain device, the retarding device and wavelength selector being mutually arranged on the base so that a resonator is established for light portions emitted by the gain device and selected by wavelength selector; this does not exclude the presence of further elements contributing to the resonator, such as additional mirrors (including resonator end mirrors), lenses, polarization selective elements, other passive optical components, etc.; wherein the beam path in the retarding device is a part of a beam path of the resonator.

Abstract: In accordance with the invention, a display apparatus comprising a light source is provided, said light source comprising at least one superluminescent light emitting diode (SLED), the apparatus further comprising at least one light modulating device arranged in a beam path of a light beam emitted by said light source and operable to emit influenced light upon incidence of said light beam, the light modulating device being operatively connected to an electronic control, the display apparatus further comprising a projection optics arranged in a beam path of said influenced light.

Abstract: In accordance with the invention, a display apparatus comprising a light source is provided, said light source comprising at least one superluminescent light emitting diode (SLED), the apparatus further comprising at least one light modulating device arranged in a beam path of a light beam emitted by said light source and operable to emit influenced light upon incidence of said light beam, the light modulating device being operatively connected to an electronic control, the display apparatus further comprising a projection optics arranged in a beam path of said influenced light.

Abstract: A swept wavelength light source is provided, the light source includes a semiconductor gain device operable to provide amplification, an optical retarding device, the retarding device having a block of material, a beam path with a well-defined beam path length being defined for light within the block of material produced by the gain device, a wavelength selector, and the gain device, the retarding device and wavelength selector being mutually arranged on the base so that a resonator is established for light portions emitted by the gain device and selected by wavelength selector; this does not exclude the presence of further elements contributing to the resonator, such as additional mirrors (including resonator end mirrors), lenses, polarization selective elements, other passive optical components, etc.; wherein the beam path in the retarding device is a part of a beam path of the resonator.

Abstract: In accordance with the invention, a light source for display and/or illumination is provided, the light source comprising a heterostructure including semiconductor layers, the heterostructure forming a waveguide between a first end and a second end, the heterostructure comprising a plurality of layers and comprising an optically active zone formed by the plurality of layers, the optically active zone capable of emitting light guided by said waveguide, at least two different radiative transitions being excitable in the optically active an electrical current between a p-side electrode and an n-side electrode, transition energies of said at least two different radiative transitions corresponding to wavelengths in the visible part of the optical spectrum, the light source further comprising means for preventing reflections of light from the waveguide by at least one of said first and second end back into the waveguide, thereby causing the light source to comprise a superluminescent light emitting diode.

Abstract: In accordance with the invention, a display apparatus comprising a light source is provided, said light source comprising at least one superluminescent light emitting diode (SLED), the apparatus further comprising at least one light modulating device arranged in a beam path of a light beam emitted by said light source and operable to emit influenced light upon incidence of said light beam, the light modulating device being operatively connected to an electronic control, the display apparatus further comprising a projection optics arranged in a beam path of said influenced light.

Abstract: In accordance with the invention, a light source for display and/or illumination is provided, the light source comprising a heterostructure including semiconductor layers, the heterostructure forming a waveguide between a first end and a second end, the heterostructure comprising a plurality of layers and comprising an optically active zone formed by the plurality of layers, the optically active zone capable of emitting light guided by said waveguide, at least two different radiative transitions being excitable in the optically active an electrical current between a p-side electrode and an n-side electrode, transition energies of said at least two different radiative transitions corresponding to wavelengths in the visible part of the optical spectrum, the light source further comprising means for preventing reflections of light from the waveguide by at least one of said first and second end back into the waveguide, thereby causing the light source to comprise a superluminescent light emitting diode.

Abstract: In accordance with the invention, a display apparatus including a light source is provided, the light source having at least one superluminescent light emitting diode (SLED), the apparatus further having at least one light modulating device arranged in a beam path of a light beam emitted by the light source and operable to emit influenced light upon incidence of the light beam, the light modulating device being operatively connected to an electronic control, the display apparatus further having a projection optics arranged in a beam path of the influenced light.

Abstract: In accordance with the invention, a display apparatus including a light source is provided, the light source having at least one superluminescent light emitting diode (SLED), the apparatus further having at least one light modulating device arranged in a beam path of a light beam emitted by the light source and operable to emit influenced light upon incidence of the light beam, the light modulating device being operatively connected to an electronic control, the display apparatus further having a projection optics arranged in a beam path of the influenced light.

Abstract: An apparatus for producing wavelength stabilized electromagnetic radiation is provided, the apparatus comprising a broadband semiconductor radiation source configured to produce broadband electromagnetic radiation having a mean wavelength ?m, and a bandpass radiation filter, an input of said bandpass radiation filter being in optical connection to an output of said radiation source, and a common temperature stabilizer being in thermal contact with both, the radiation source and the radiation filter. In a preferred embodiment, the radiation source—which is, for example, a superluminescent light emitting diode—and the bandpass radiation filter are provided on a common mount which is in contact with a thermoelectric cooler acting, together with temperature sensing means and control means, as temperature stabilizer.

Abstract: An apparatus for producing wavelength stabilized electromagnetic radiation is provided, the apparatus comprising a broadband semiconductor radiation source configured to produce broadband electromagnetic radiation having a mean wavelength ?m, and a bandpass radiation filter, an input of said bandpass radiation filter being in optical connection to an output of said radiation source, and a common temperature stabilizer being in thermal contact with both, the radiation source and the radiation filter. In a preferred embodiment, the radiation source—which is, for example, a superluminescent light emitting diode—and the bandpass radiation filter are provided on a common mount which is in contact with a thermoelectric cooler acting, together with temperature sensing means and control means, as temperature stabilizer.

Abstract: A non-lasing superluminescent light emitting diode (SLED) comprises a semiconductor heterostructure forming a PN junction and a waveguide defining an optical beam path. The heterostructure includes a gain region and an absorber region in series with the gain region in the optical beam path. A voltage is applied to the PN junction in the gain region by first contact means, so that light emission from the active region and along the optical beam path is produced. According to the invention, second contact means are provided, contacting the PN junction in the absorber region and operable to remove charge carriers generated by absorption in the absorber region. The second contact means are not connected to a voltage source, but to a charge carrier reservoir such as a metal surface. According to a preferred embodiment, the two end facets of the waveguide are perpendicular to the optical beam path.