An apparatus for generating electromagnetic radiation includes a pump laser so adapted that in operation of the apparatus it generates electromagnetic continuous-wave pump radiation; an optical parametric oscillator which is arranged in the beam path of the pump radiation and has a non-linear optical crystal, and is so adapted that in operation of the apparatus it generates signal and idler radiation from the pump radiation, and a non-linear optical device having a non-linear optical crystal, being arranged at least in a beam path of the signal radiation or idler radiation, and being so adapted that in operation of the apparatus it generates from the signal or idler radiation electromagnetic radiation at a frequency greater than a frequency of the signal or idler radiation. The non-linear optical crystal being heated in a furnace so that the crystal has a temperature gradient in the beam direction of the signal or idler radiation.

A method of creating difference frequency (DF) laser pulses (1) by difference frequency generation (DFG) comprises the steps of providing ultrashort laser pulses (2) having a spectral bandwidth corresponding to a Fourier limit of below 50 fs and containing first spectral components and second spectral components having larger frequencies than the first spectral components, and driving a DFG process by the ultrashort laser pulses (2) in an optically non-linear crystal (10), wherein the DF laser pulses (1) are generated in the crystal (10) by difference frequencies between the first and second spectral components, resp., said difference frequencies comprising third spectral components being lower in frequency than the first and second spectral components, wherein at least one enhancement cavity (20) with resonator mirrors (Mil to Ml4) spanning a beam path (22) is provided and the crystal (10) is placed in the beam path (22) of the enhancement cavity (20), the ultrashort laser pulses (2) are input coupled and coherently added in the at least one enhancement cavity (20), at least one circulating ultrashort laser pulse (3) is created in the at least one enhancement cavity (20), which drives the DFG process in the crystal (10) for generating the DF laser pulses (1), and the at least one enhancement cavity (20) is adapted for recycling the at least one ultrashort laser pulse (3) passing through the crystal (10). Furthermore, a photonic source (100) for creating DF laser pulses (1) is described, including one or more enhancement cavities.

A continuously tunable radio frequency (RF) sensor system is provided. The system includes a pump laser system that includes first and second pump lasers, at least one frequency modulator to modulate frequencies of first and second laser light from the pump lasers to first and second select frequencies, a switch system to selectively pass one of the first and second laser light, an amplifier to amplify the passed laser light, a frequency doubler to double the frequency of the amplified laser light to generate pump light. A laser source lock system is in communication with the pump laser system to ensure a frequency of the pump light is referenced to atoms in a vapor cell and provide a probe light. The pump light and probe light are transmitted through the vapor cell. A detector measures the probe light that passed through the vapor cell.

Embodiments of the present invention relate to methods and apparatus for detecting atmospheric NO at signal levels capable of distinguishing the NO isotopologues. More particularly, embodiments of the present invention relate to methods and apparatus for a single photon LIF sensor that pumps a vibronic transition near 215 nm and observes the resulting red shifted fluorescence from about 255 to about 267 nm. Embodiments of the present system uses a NO-LIF measurement fiber-amplified laser apparatus capable of: generating laser linewidth that is sufficiently narrow to resolve the Doppler broadened NO spectrum at room temperature and thereby achieve high signal levels and distinguish the NO isotopologues; generating laser repetition rate sufficient to enable single-photon counting of the fluorescence signal; and having size, weight and environmental robustness allowing for integration onto airborne platforms.

According to some aspects, a transmissive and all-dielectric optical component/limiter with great cutoff efficiency using Vanadium Dioxide (VO.sub.2) as the active component is disclosed. In some embodiments, Vanadium dioxide is used for an optical limiter due to the large contrast in optical constants upon undergoing the semiconductor to metal phase transition. When triggered optically, this transition occurs within 60 fs, making the device suitable for an ultrafast laser environment. In addition, the phase transition threshold is tunable by applying stress or doping; therefore, the device cutoff intensity can be adjusted to fulfill specific requirements.

A nonlinear crystal including stacked Strontium tetraborate SrB.sub.4O.sub.7 (SBO) crystal plates that are cooperatively configured to create a periodic structure for quasi-phase-matching (QPM) is used in the final frequency converting stage of a laser assembly to generate laser output light having a wavelength in the range of 125 nm to 183 nm. One or more fundamental light beams having fundamental wavelengths between 1 and 1.1 μm are doubled and/or summed using multiple intermediate frequency conversion stages to generate one or more intermediate light beam frequencies (e.g., second through eighth harmonics, or sums thereof), and then the final frequency converting stage utilizes the nonlinear crystal to either double a single intermediate light beam frequency or to sum two intermediate light beam frequencies to generate the desired laser output light at high power and photon energy levels. A method and inspection system incorporating the laser assembly is also described.

A wavelength conversion system according to an aspect of the present disclosure includes a first crystal holder holding a first non-linear crystal, a second crystal holder holding a second non-linear crystal, a third crystal holder holding a third non-linear crystal, and a container housing the holders. The container has an entrance window and an emission window. The first non-linear crystal, the second non-linear crystal, and the third non-linear crystal are disposed in this order on an optical path of a laser beam traveling from the entrance window to the emission window. The crystal holders are rotatable. A first rotational axis that is a rotational axis of the first crystal holder is orthogonal to a second rotational axis that is a rotational axis of the second crystal holder, and the first rotational axis is parallel to a third rotational axis that is a rotational axis of the third crystal holder.

In a laser system according to an aspect of the present disclosure, the following components are disposed: a first container that accommodates a first heater and a first crystal holder holding a first nonlinear crystal and includes a first light incident window via which laser light is incident and a first light exit window via which the laser light exits; a second container that accommodates a second heater and a second crystal holder holding a second nonlinear crystal and includes a second light incident window via which the laser light is incident and a second light exit window via which the laser light exits; and a stage that holds the first and second containers. A controller controls the stage to move the first nonlinear crystal away from the optical path of the laser light and inserts the second nonlinear crystal into the optical path of the laser light.

Methods and apparatuses for manipulating and modulating of laser beams. The methods and apparatuses enable activating and deactivating of laser beams, while the laser systems maintain their operating power. Further, a hybrid pump module configured to be coupled to an optical fiber having a core and at least one clad, comprising: at least one focusing lens in optical with the optical fiber; plurality of diode modules, each configured to output a multi-mode beam in optical path with the clad; and at least one core associated module, in optical path with the core, configured to provide selected functions. Further, apparatus and methods configured for frequency doubling of optical radiation.

A laser apparatus according to an aspect of the present disclosure includes a plurality of semiconductor lasers, a plurality of optical switches disposed in the optical paths of the plurality of respective semiconductor lasers, a wavelength conversion system configured to convert pulsed beams outputted from the plurality of optical switches in terms of wavelength to generate wavelength-converted beams, an ArF excimer laser amplifier configured to amplify the wavelength-converted beams, and a controller configured to control the operations of the plurality of semiconductor lasers and the plurality of optical switches, and the plurality of semiconductor lasers are each configured to output a laser beam so produced that wavelengths of the wavelength-converted beams are wavelengths at which the ArF excimer laser amplifier performs amplification and differ from the optical absorption lines of oxygen.