In an embodiment, a laser includes a gain section. The gain section includes an active region, an upper separate confinement heterostructure (SCH), and a lower SCH. The upper SCH is above the active region and has a thickness of at least 60 nanometers (nm). The lower SCH is below the active region and has a thickness of at least 60 nm.

A wavelength estimation device including a light detector to receive light emitted from a light source and an estimation unit. The estimation unit estimates a wavelength of the light based on an amount of light received by the light detector.

Nanolaser arrays have certain advantages over LEDs and conventional laser diodes for solid-state lighting applications. In particular, nanocavities can channel spontaneous emission entirely into the lasing mode, so that all the emissions (spontaneous and stimulated) contribute to usable light output over a large range of current.

A distributed feedback laser, including: an output end including an active region including a grating including a λ/4 phase-shift region; and a non-output end including a reflecting region including a grating with uniform period. The length of the active region is smaller than or equal to 200 μm. The end facet of the output end of the laser is coated with an anti-reflection film.

A method for numerical control milling, forming and polishing of a large-diameter aspheric lens to solve long time-consuming and severe tool wear in the machining of a meter-scale large-diameter aspheric surface is disclosed. An aspheric surface is discretized into a series of rings with different radii, and the rings are sequentially machined through generating cutting by using an annular grinding wheel tool; the rings are equally spaced, there are a total of N rings, and the width of any ring is jointly determined by the N.sup.th ring, the (N-1)th ring, positioning accuracy, and a generatrix equation of the aspheric lens, and the n.sup.th ring has a curvature radius of Rn =sqrt(R0.sup.2-k*(n*dx).sup.2); and the aspheric surface is enveloped by a large number of rings. The tool used for machining has a diameter greater than the semi-diameter of the aspheric surface, and contact area between tool and workpiece surface is rings.

An apparatus is configured to operate in a single fundamental transverse mode and the apparatus includes a waveguide layer between an n-doped cladding layer and a p-doped cladding layer. The waveguide layer includes a first waveguide part, and an active layer located between the first waveguide part and the p-doped cladding layer, the active layer being asymmetrically within the waveguide layer closer to the p-doped cladding layer than the n-doped cladding layer. The refractive index of the n-doped cladding layer being equal to or larger than the p-doped cladding layer. A first end of the first waveguide part is adjacent to the n-doped cladding layer. A second end of the first waveguide part is adjacent to a first end of the active layer. A desired donor density is doped in the first waveguide part for controlling the carrier density dependent internal optical loss in the first waveguide part at high injection levels.

In some implementations, a device may generate a data set including at least modal gain values and modal loss values for a semiconductor optical amplifier (SOA) slice. The device may determine, based on the data set, respective widths for a plurality of slices of an SOA using an autoregressive model. A width, of the respective widths, for a slice, of the plurality of slices, may be associated with a maximum conversion efficiency achievable for the slice at a given current density. The device may generate information indicating a geometry for the SOA based on the respective widths for the plurality of slices.

Methods for designing a mode-selective optical device including one or more optical interfaces defining an optical cavity include: defining a loss function within a simulation space encompassing the optical device, the loss function corresponding to an electromagnetic field having an operative wavelength within the optical device resulting from an interaction between an input electromagnetic field at the operative wavelength and the one or more optical interfaces of the optical device; defining an initial structure for each of the one or more optical interfaces, each initial structure being defined using a plurality of voxels; determining values for at least one structural parameter and/or at least one functional parameter of the one or more optical interfaces by solving Maxwell's equations; and defining a final structure of the one or more optical interfaces based on the values for the one or more structural and/or functional parameters.

A semiconductor light-emitting element includes: a substrate; an n-type clad layer above the substrate; an active layer above the n-type clad layer; and a p-type clad layer above the active layer. The active layer includes: a well layer; an n-side first barrier layer on an n-type clad layer side of the well layer; and a p-side barrier layer on a p-type clad layer side of the well layer. The p-side barrier layer comprises In. The n-side first barrier layer has an In composition ratio lower than an In composition ratio of the p-side barrier layer. The n-side first barrier layer has a band gap energy smaller than a band gap energy of the p-side barrier layer.

Time-of-flight (ToF) systems which use pulsed laser diodes, are required to measure distances with high level of precision and control. The present disclosure provides a method and a corresponding system for controlling a temporal response of a laser diode, in particular pulsed laser diodes. In particular, the present disclosure provides a method and a related system for driving a laser diode so as to obtain predominantly a peak pulse response while minimising or completely avoiding the post-peak response in a temporal response of the laser diode.