An etched planarized VCSEL includes: an active region; a blocking region over the active region, and defining apertures therein; and conductive channel cores in the apertures, wherein the conductive channel cores and blocking region form an isolation region. A method of making the VCSEL includes: forming the active region; forming the blocking region over the active region; etching the apertures in the blocking region; and forming the conductive channel cores in the apertures of the blocking region. Another etched planarized VCSEL includes: an active region; a conductive region over the active region, and defining apertures therein; and blocking cores in the apertures, wherein the blocking cores and conductive region form an isolation region. A method of making the VCSEL includes: forming the active region; forming the conductive region over the active region; etching the apertures in the conductive region; and forming the blocking cores in the apertures of the conductive region.

A laser apparatus includes: an oscillator configured to output seed light; an amplifier including a laser chamber provided in an optical path of the seed light and a pair of discharge electrodes provided inside the laser chamber; and a transform optical system provided in the optical path of the seed light between the oscillator and the amplifier and configured to transform the seed light in a way that suppresses a decrease in purity of polarization of a laser beam that is outputted from the amplifier.

Laser apparatus includes an output coupler, a gain medium for generating laser light, a rear optical element, and an input coupler. The input coupler is arranged to direct a pump beam to the gain medium and to define an optical path between the output coupler and the rear optical element. The rear optical element is a spatial light modulator arranged to act as an intra-cavity digital holographic mirror which can be digitally addressed. The spatial light modulator displays selectively a gray-scale image of a hologram thereby to phase-modulate laser light in the cavity, thus making it possible to generate an output laser beam having a desired characteristic. The apparatus includes a computer arranged to generate at least one hologram corresponding to a desired output beam characteristic, and a driver circuit responsive to an output from the computer to generate a corresponding gray-scale image of the hologram on the spatial light modulator.

A nano Bessel laser beam emitter and a method for manufacturing the same are disclosed. The nano Bessel laser beam emitter includes a first Bragg reflecting layer, a light-emitting layer and a second Bragg reflecting layer, where the first Bragg reflecting layer defines a cylindrical through hole; the light-emitting layer is provided on a surface of the first Bragg reflecting layer and is configured to generate a light beam; and the second Bragg reflecting layer is provided on the light-emitting layer at a side distal to the first Bragg reflecting layer.

Various example embodiments relate to active optical fibers and devices using active optical fibers. An active optical fiber may comprise a central part surrounded by an annular active core. The fiber may have a tapered longitudinal profile such that the fiber comprises a single-mode portion and a multimode portion. The annular core may have low birefringence, obtained for example by rotating (spinning) the fiber preform during manufacture of the fiber. Refractive index of the annular core may be higher than the refractive indices of the central part and cladding layer(s) surrounding the annular core. The active optical fiber enables selective generation or amplification of light modes with orbital angular momentum (OAM). Furthermore, the fiber has a large mode field diameter (MFD) and it is not sensitive to internal heating or environmental influences.

Various embodiments may provide a topological laser. The topological laser may include a photonic structure configured to generate a laser beam upon electrical pumping of the photonic structure. The laser beam may be based on photonic Majorana zero mode. The laser beam may be a cylindrical vector beam. The topological laser may be configured to provide single mode operation.

An optical oscillator includes a first reflection part configured to reflect light of a first wavelength, a laser medium excited by excitation light of a second wavelength different from the first wavelength and configured to emit light of the first wavelength, a second reflection part configured to form an unstable resonator together with the first reflection part, the unstable resonator being configured to output annular laser light of the first wavelength, and a saturable absorption part disposed between the laser medium and the second reflection part and of which a transmittance increases with absorption of light of the first wavelength. When a power of the excitation light is indicated by P.sub.p (kW), and an inner diameter of the annular laser light is indicated by d.sub.i, and an outer diameter is indicated by d.sub.o, and d.sub.o/d.sub.i is a magnification m, the magnification m satisfies a.sub.0+a.sub.1 Log(P.sub.p)mb.sub.0+b.sub.1P.sub.p+b.sub.2P.sub.p.sup.2.

A beam shaper includes upstream and downstream fibers fused together at a splice angle different from a zero angle and controllably increased to provide a transformation of a Gaussian intensity distribution profile at an input of the upstream fiber to an intensity distribution profile including one of flattop, inverse Gaussian and donut-shaped profiles at an output of the downstream fiber. The fibers are selected from SM, MM passive and active fibers with the downstream fiber being a multimode fiber.