A monomode optical fiber, and a process for manufacturing such a fiber, that comprises a monomode core and at least one cladding encircling the core. The monomode core comprises at least two zones, a first zone with at least one first refractive index and a second zone with at least one second refractive index different from the first refractive index. The difference between the first refractive index and the second refractive index is of the same order of magnitude as the variation in the refractive index of the second zone between the inactive state and the active state of the fiber.

A laser projection module, a depth camera and an electronic device are provided. The laser projection module includes a laser emitter, a collimation element, a diffractive optical element and a temperature detection element. The laser emitter is configured to emit laser. The collimation element is arranged in a laser emission direction of the laser emitter and configured to collimate the laser. The diffractive optical element is arranged in a position subsequent to the collimation element along the laser emission direction of the laser emitter, and configured to diffract the laser collimated by the collimation element to form a laser pattern. The temperature detection element is arranged adjacent to the laser emitter and configured to detect a temperature of the laser emitter.

A burst logging system logs and transmits to a local or remote computing system event data related to errors in and or potential failures of laser system components. The system further provides for capturing data at different rates from different sensors, synchronization of data capture associated with system events and the possibility for aggregation of data from multiple systems, which can in turn be leveraged to predict and or remediate future system events.

A monitoring device may receive sensor information, associated with an optical device included in a high-power fiber laser, from a set of sensors associated with the optical device. The monitoring device may determine, based on the sensor information, a set of operational properties of the optical device. The set of operational properties may include: a health property that describes a health of one or more components of the optical device, a degradation property that describes degradation of one or more components of the optical device, an environmental property that describes an environment of the optical device, or a process property associated with a process in which the optical device is being used. The monitoring device may identify whether an operational property, of the set of operational properties, satisfies a condition, and may selectively perform a monitoring action based on whether the operational property satisfies the condition.

Direct diode-pumped Ti:sapphire laser amplifiers use fiber-coupled laser diodes as pump beam sources. The pump beam may be polarized or non-polarized. Light at wavelengths below 527 nm may be used in cryogenic configurations. Multiple diode outputs may be polarization or spectrally combined.

The present disclosure provides an apparatus and a method for measuring a concentration of pollutants in water. A passive Q-switched fiber laser outputs an evanescent wave to a to-be-tested water sample after emitting a Q-switched pulse laser signal and transmitting it via an evanescent field fiber, and based on an evanescent wave change caused by an absorption effect of the pollutants in the to-be-tested water sample to the evanescent wave and an output repetition frequency change of the passive Q-switched fiber laser due to the evanescent wave change, outputs an output repetition frequency result of the passive Q-switched fiber laser. The method is simple; and the apparatus based on the method is simple in structure and low in cost.

Fiber lasers and methods are provided, in which the modal instability threshold is raised to provide more laser power. Fiber lasers comprise an active optical fiber having at least one absorption peak wavelength (.sub.peak) and capable of supporting more than a fundamental mode during operation, and a plurality of pump diodes connected to deliver radiation emitted thereby into the optical fiber. At least one of the pump diodes is a wavelength-locked (WL) diode and at least one of the pump diodes is configured to deliver radiation at at least (not necessarily the same diode(s)). The pump diodes may comprise any of WL diode(s) at .sub.peak, WL diode(s) at =.sub.peak and non-WL diode(s). Pumping radiation off the fiber's absorption peak increases the modal instability threshold, most likely by reducing the temperature gradient in the active fiber at the fiber pump entrance point and along the fiber.

An optical gain fiber for use in high power (e.g., greater than 500 W pump power) is proposed that is configured to exhibit a minimum bend radius such that the bend loss for the propagating LP.sub.01 mode is greater than about 0.03 dB/m. It has been discovered that this bend radius criteria, which is less stringent than that typically suggested in the art (e.g., bend loss less than about 0.03 dB/m), meets the modal stability requirements at high power operation, since the increase in operating temperature of the fiber laser or amplifier has been found to somewhat relax the bend radius requirement (which was heretofore only measured at room temperature, not operating temperature). Modal stability is defined in terms of a reduced presence of unwanted higher-order modes (such as the LP.sub.11 mode) in the amplified output signal.

A laser oscillator having a condensation prevention mechanism capable of extending the life span of a light emitting device while maintaining cost effectiveness as compared to the conventional technique is provided. The laser oscillator includes: a laser beam generating unit; a heat exchanger; a coolant bypass circuit; a coolant circuit connecting these components; a housing storing these components; a coolant circulating unit that circulates a coolant to the laser beam generating unit, the heat exchanger, and the coolant bypass circuit with the aid of the coolant circuit; a first valve that adjusts a flow rate of the coolant supplied to the laser beam generating unit; a second valve that adjusts a flow rate of the coolant supplied to the heat exchanger; a third valve that adjusts the flow rate of the coolant supplied to the coolant bypass circuit; a dew point measuring unit that measures a dew point inside the housing; a temperature measuring unit that measures a coolant temperature; and a control unit that controls the first, second, and third valves on the basis of the dew point and the coolant temperature.

A device and method for tuning a ring resonator using self-heating stabilization is provided. A light source is controlled to produce an optical signal, input to an optical ring resonator, at a power where self-heating shifts a resonance wavelength of the optical ring resonator by at least 10 picometers, the self-heating comprising absorption in the optical ring resonator of optical power from a received optical signal. Prior to using the optical ring resonator at least one of modulate and filter the optical signal at the optical ring resonator, a heater of the optical ring resonator is controlled to an operating temperature at which the resonance wavelength of the optical ring resonator is greater than a respective wavelength of the optical signal.