A system includes a waveguide and an edge-emitting laser. The edge-emitting laser is configured to lase coherent light into the waveguide. The edge-emitting laser includes an optical cavity having an active gain section and a passive section. The active gain section is configured to amplify an optical power of light reflecting within the optical cavity. The passive section increases a functional length of the optical cavity such that a total length of the optical cavity reduces fringe interference of the coherent light propagating through the waveguide.

An edge-emitting laser including a substrate, a lower power optical cavity located on the substrate and a higher power optical cavity located on the substrate adjacent the lower power optical cavity. The lower power optical cavity includes a first active gain section having a first length. The higher power optical cavity includes a second active gain section having a second length greater than the first length.

A semiconductor laser is for generating colored light. The semiconductor laser oscillates in a longitudinal multimode. A width of a wavelength band with an intensity equal to or more than 20 dB relative to a peak intensity in a spectrum distribution of output light is equal to or less than 15 nm. A light source device may include The semiconductor laser; a wavelength estimating device configured to estimate a wavelength of light from the semiconductor laser; and an emission-light intensity setting unit configured to set an emission light intensity of the semiconductor laser in accordance with an estimation result by the wavelength estimating device.

A semiconductor laser source including a Mach-Zehnder interferometer, this interferometer including first and second arms. Each of the arms is divided into a plurality of consecutive sections, the effective index of each section located immediately after a preceding section being different from the effective index of this preceding section. The lengths of the various sections meet the following condition:

[00001]$\underset{n=1}{\overset{N_2}{.Math.}}.Math.L_{2,n}.Math.{\mathrm{neff}}_{2,n}-\underset{n=1}{\overset{N_1}{.Math.}}.Math.L_{1,n}.Math.{\mathrm{neff}}_{1,n}=k_f.Math.{}_{\mathrm{Si}}$

where: k.sub.f is a preset integer number higher than or equal to 1, N.sub.1 and N.sub.2 are the numbers of sections in the first and second arms, respectively, L.sub.1,n and L.sub.2,n are the lengths of the nth sections of the first and second arms, respectively, neff.sub.1,n and neff.sub.2,n are the effective indices of the nth sections of the first and second arms, respectively. The first and second arms each comprise a gain-generating section.

A semiconductor laser device with external resonator with stable longitudinal mode regardless of variation of drive current is disclosed. The device includes: a semiconductor light-emitting element having a pair of end faces with a light emitting section disposed therebetween, and an external resonator configured to oscillate light emitted from the semiconductor light-emitting element, the external resonator being formed by a resonator mirror disposed outside the semiconductor light-emitting element and one of the pair of end faces that is farther from the resonator mirror, wherein, as the semiconductor light-emitting element, a semiconductor light-emitting element having a structure which does not oscillate light emitted therefrom by itself is used. The device further includes a wavelength control element disposed in the optical path within the external resonator and configured to select a wavelength range of the light, and a driver circuit configured to perform fast modulation drive of the semiconductor light-emitting element.

A system and method for providing laser diodes with broad spectrum is described. GaN-based laser diodes with broad or multi-peaked spectral output operating are obtained in various configurations by having a single laser diode device generating multiple-peak spectral outputs, operate in superluminescence mode, or by use of an RF source and/or a feedback signal. In some other embodiments, multi-peak outputs are achieved by having multiple laser devices output different lasers at different wavelengths.

Systems and methods are provided for controlling and/or modifying operation of a red, green, blue (RGB) laser assembly for creating images in mixed-reality environments. Initially, the lasers in the RGB laser assembly operate in a low power or non-emitting state. Then, the lasers emit laser light to illuminate a pixel or a group of pixels. This illumination occurs for a period of time spanning less than 15 nanoseconds. By causing the lasers to emit laser light only during this short period of time, the resulting laser light is structured with a reduced spatial coherence level. Once the time period elapses, then the lasers again return to the non-emitting state. This process repeats for each pixel such that the lasers generate pulsed emissions. By operating the lasers with a reduced spatial coherence, undesired visual artifacts can be reduced or eliminated within the target display area.

A holographic observation method includes: casting a light beam generated by driving a semiconductor laser light source with an electric current with an alternating-current component superimposed or a light beam having a predetermined spectral width and predetermined spectral intensity to have predetermined coherency to an observation object; forming a hologram by causing a light beam transmitted through or reflected by the observation object to interfere with a reference light beam; and obtaining information on the observation object by performing image processing on the hologram.

Conventional integrated optical amplifiers, which combine different types of platforms, e.g. silicon photonic integrated circuit for the device layer, and a Group III-V material for the gain medium, typically include a curved waveguide extending through the gain medium coupled to waveguides in the main device layer. Unfortunately, the radius of curvature of the curved waveguide becomes a limiting factor for both size and amplification. Accordingly, an optical amplifier which eliminates the need for the curved waveguide by including a coupler for splitting an input optical signal into two sub-beams, for passage through the gain medium, and a reflector for reflecting the two sub-beams back through the gain medium to the coupler for recombination, would be a welcome improvement. A phase tuner may also be provided to ensure coherence cancellation between the two sub-beams to maximize output and minimize back reflection without requiring an isolator.

A semiconductor laser is for generating colored light. The semiconductor laser oscillates in a longitudinal multimode. A width of a wavelength band with an intensity equal to or more than 20 dB relative to a peak intensity in a spectrum distribution of output light is equal to or less than 15 nm. A light source device may include The semiconductor laser; a wavelength estimating device configured to estimate a wavelength of light from the semiconductor laser; and an emission-light intensity setting unit configured to set an emission light intensity of the semiconductor laser in accordance with an estimation result by the wavelength estimating device.