76 results about "Lasing threshold" patented technology

A wavelength tunable laser comprising a laser diode and a closed external cavity formed by one or more optical resonators either horizontally or vertically coupled to adjacent waveguides. The optical resonator primarily functions as a wavelength selector and may be in the form of disk, ring or other closed cavity geometries. The emission from one end of the laser diode is coupled into the first waveguide using optical lens or butt-joint method and transferred to the second waveguide through evanescent coupling between the waveguides and optical resonator. A mirror system or high reflection coating at the end of the second waveguide reflects the light backwards into the system resulting in a closed optical cavity. Lasing can be achieved when the optical gain overcomes the optical loss in this closed cavity for a certain resonance wavelength which is tunable by changing the resonance condition of the optical resonator through reversed biased voltage or current injection. Multiple optical resonators may be used to reduce the lasing threshold and provide higher power output. With monolithic integration, more optical devices can be integrated with the tunable laser into the same substrate to produce optical devices that are capable of more complex functions, such as tunable transmitters or waveguide buses.

Lasing at the edge of the reflection band or at a defect state within the reflection band of a thin one-dimensional feedback structure is used to create a large-area, thin-film laser source with transverse dimensions that can be much greater than the film thickness. Angular confinement of radiation propagating perpendicular to the layers leads to a spreading of the beam inside the medium which is much greater than the diffraction divergence. This enhances the spatial extent of correlation at the output surface of the thin film. When a pump source induces gain at the lasing threshold in a wide region, a spatially coherent monochromatic light beam is emitted perpendicular to the film surface from the entire gain region. Alternate embodiments of the present invention include a passive spatial filter and an active amplifier.

A directly driven laser includes multiple contacts, with at least one of the contacts for injecting current into the laser such that the laser reaches at least a lasing threshold and at least one of the contacts for providing a data signal to the laser. In some embodiments a differential data signal is effectively provided to a front and a rear section of the laser, while lasing threshold current is provided to a central portion of the laser.

A quantum random number generator (QRNG) and a photon generator for a QRNG are provided. The photon generator may be operated in a spontaneous mode below a lasing threshold to emit photons. Photons emitted from the photon generator may have at least one random characteristic, which may be monitored by the QRNG to generate a random number. In one embodiment, the photon generator may include a photon emitter and an amplifier coupled to the photon emitter. The amplifier may enable the photon generator to be used in the QRNG without introducing significant bias in the random number and may enable multiplexing of multiple random numbers. The amplifier may also desensitize the photon generator to fluctuations in power supplied thereto while operating in the spontaneous mode. In one embodiment, the photon emitter and amplifier may be a tapered diode amplifier.

The invention relates to a laser device, comprising a laser material (1) brought into a simmer mode. A controllable source (7, 17) of additional energy (16, 20) supplies energy to the laser material (1), such that in only a desired part of the laser material (1) a lasing threshold is exceeded, and a laser beam (10) is emitted from only a desired part of the laser surface. This device makes possible to provide a laser beam in just the desired part of the laser, which allows a flexible and localized output. The invention further relates to a hair- removing device comprising a laser device according to the invention and further comprising an optical system(6) for focusing the laser beam pulses on a focal spot (12) and for positioning the focal spot in a target position, wherein the optical system (6) comprises a movable lens or a plurality of individually addressable lenses.

A pulsed laser system having a Tm3+-doped saturable absorber Q-switch unit, capable of outputting laser pulses sequentially by inputting a stable continuous-wave pump light source, is disclosed. When the gain excited in the Er3+ laser resonator exceeds the lasing threshold, the photons start resonating and being amplified in the Er3+ laser resonator. At the same moment, the Tm3+-doped saturable absorber Q-switch unit absorbs the resonant photons and quickly reaches the situation of absorption saturation. Then, sequentially Q-switched Er3+ laser pulses at 1570 nm are passively produced. In addition, the Tm3+-doped saturable absorber Q-switch unit can be designated as the gain material of a second laser resonator for producing a gain-switched Tm3+ laser pulse at 1950 nm after each of the Q-switched Er3+ laser pulses. Moreover, the Tm3+ and Ho3+ co-doped crystal can be designated as the saturable absorber Q-switch unit, for producing a gain-switched Ho3+ laser pulses at 2090 nm.

A Ho:YAG crystal laser is disclosed which is doped with less than 2% holmium to reduce the lasing threshold and up-conversion, thereby increasing the operating efficiency of the laser. The laser does not need sensitizer ions so energy mismatches introduced by the sensitizer ions ale eliminated to the thereby increase the efficiency of the laser while minimizing detrimental thermal loading in the laser caused by up-conversion loss processes. The Ho:YAG crystal laser is directly pumped by a Thulium fiber laser at 1.9 μm at the holmium 5I7 to 5I8 transition to produce an output at 2.1 μm yielding a very low quantum defect. The laser is embodied as a thulium fiber laser pumped oscillator or an amplifier.

A quantum random number generator (QRNG) and a photon generator for a QRNG are provided. The photon generator may be operated in a spontaneous mode below a lasing threshold to emit photons. Photons emitted from the photon generator may have at least one random characteristic, which may be monitored by the QRNG to generate a random number. In one embodiment, the photon generator may include a photon emitter and an amplifier coupled to the photon emitter. The amplifier may enable the photon generator to be used in the QRNG without introducing significant bias in the random number and may enable multiplexing of multiple random numbers. The amplifier may also desensitize the photon generator to fluctuations in power supplied thereto while operating in the spontaneous mode. In one embodiment, the photon emitter and amplifier may be a tapered diode amplifier.