A surface-emitting semiconductor laser system contains at least one MQW unit of at least three constituent QWs, axially separated from one another substantially non-equidistantly. The MQW unit is located within the axial extent covered, in operation of the laser, by a half-cycle of the standing wave of the field at a wavelength within the gain spectrum of the gain medium; immediately neighboring nodes of the standing wave are on opposite sides of the MQW unit. So-configured MQW unit can be repeated multiple times and/or complemented with individual QWs disposed outside of the half-cycle of the standing wave with which such MQW unit is associated. The semiconductor laser further includes a pump source configured to input energy in the semiconductor gain medium and a mode-locking element to initiate mode-locking.

A surface-emitting semiconductor laser system contains at least one MQW unit of at least three constituent QWs, axially separated from one another substantially non-equidistantly. The MQW unit is located within the axial extent covered, in operation of the laser, by a half-cycle of the standing wave of the field at a wavelength within the gain spectrum of the gain medium; immediately neighboring nodes of the standing wave are on opposite sides of the MQW unit. So-configured MQW unit can be repeated multiple times and/or complemented with individual QWs disposed outside of the half-cycle of the standing wave with which such MQW unit is associated. The semiconductor laser further includes a pump source configured to input energy in the semiconductor gain medium and a mode-locking element to initiate mode-locking.

The present invention relates to a Vertical-Cavity Surface-Emitting Laser (VCSEL) die comprising a VCSEL array configured for flip chip bonding to a substrate with the VCSEL array being designed for emission from a substrate side of the chip, integrated beam shaping optics and electrical contacts including a top surface contact and an etched metal connection through a top mirror structure to a bottom n-mirror, or to an n-doped buffer layer under the bottom n-mirror or to the substrate. The invention further relates to an assembly comprising the above VCSEL die and a photodetector in which the VCSEL die is attached to a circuit board or sub-mount with a solder or bump bonds on the VCSEL die and the photodetector is placed on a same circuit board or sub-mount right next to the VCSEL die.

A passively mode-locking laser and corresponding method is described. The laser comprises a resonator (2) terminated by first (3) and second (4) mirrors and folded by a third (5) and fourth (6) mirror. The third mirror comprises a reflector (14) surmounted by a multilayer semiconductor gain medium (15) including at least one quantum well layer while the second mirror (4) comprises an intensity saturable mirror. The resonator is configured to provide a cross sectional area of an intra cavity resonating field on the intensity saturable mirror that is greater than or equal to a cross sectional area of the intra cavity resonating field on the multilayer semiconductor gain medium. This arrangement provides a passively mode-locking laser that exhibits increased stability when compared to those systems known in the art.

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 surface-emitting semiconductor laser system contains at least one MQW unit of at least three constituent QWs, axially separated from one another substantially non-equidistantly. The MQW unit is located within the axial extent covered, in operation of the laser, by a half-cycle of the standing wave of the field at a wavelength within the gain spectrum of the gain medium; immediately neighboring nodes of the standing wave are on opposite sides of the MQW unit. So-configured MQW unit can be repeated multiple times and/or complemented with individual QWs disposed outside of the half-cycle of the standing wave with which such MQW unit is associated. The semiconductor laser further includes a pump source configured to input energy in the semiconductor gain medium and a mode-locking element to initiate mode-locking.

A vertical external cavity surface emitting laser (VECSEL) structure includes a heterostructure and first and second reflectors. The heterostructure comprises an active region having one or more quantum well structures configured to emit radiation at a wavelength, .sub.lase, in response to pumping by an electron beam. One or more layers of the heterostructure may be doped. The active region is disposed between the first reflector and the second reflector and is spaced apart from the first reflector by an external cavity. An electron beam source is configured to generate the electron beam directed toward the active region. At least one electrical contact is electrically coupled to the heterostructure and is configured to provide a current path between the heterostructure and ground.

A laser device is provided for generating an optical wave at a laser frequency, including (i) a semiconductor element having a gain region with quantum wells, the gain region being located between a first mirror and an exit region defining an optical microcavity, (ii) a second mirror distinct from the semiconductor element and arranged so as to form with the first mirror an external optical cavity including the gain region, (iii) a pump for pumping the gain region so as to generate the optical wave, wherein the optical microcavity with the gain region and the external optical cavity are arranged so that a spectral ratio between the Half Width Half Maximum (HWHM) spectral bandwidth of the modal gain and a free spectral range of the external cavity in the range of 2 to 50.

A Vertical Cavity Surface Emitting Laser (VCSEL) includes a reflecting surface of the VCSEL. A gain region is positioned on the distributed Bragg reflector that generates optical gain. The gain region comprises a first and second multiple quantum well stack, a tunnel junction positioned between the first and second multiple quantum well stack, and a current aperture positioned on one of the first and second multiple quantum well stack. The current aperture confines a current flow in the gain region. A partially reflective surface and the reflective surface forming a VCSEL resonant cavity, wherein an output optical beam propagates from the partially reflecting surface.

An optically pumped semiconductor disk laser including a pump light source, at least one semiconductor body (2), which semiconductor body (2) has at least one window region (8), an active region (7) and a reflection device (P), which reflection device has at least one first P-reflection element (P1) for the pump wavelength. The first P-reflection element (P1) is embodied and arranged such that pump light emerging from the pump light source (3) can be guided for at least two passes through the active region (7). A total thickness of the active region (7) and of the window region (8) in the direction of an optical axis of the semiconductor disk laser is less than three times the laser wavelength in the active region (7).