A system for measuring an absorption coefficient of a doped optical fiber may include: a laser source configured to transmit laser light at a selectable wavelength; a single-mode optical fiber including an end configured to splice to the doped optical fiber; two or more multimode fibers at a side of the doped optical fiber, spaced apart along the side of the doped optical fiber, configured to collect spontaneous emissions from the side of the doped optical fiber; and/or a photodiode or power meter connected to the two or more multimode fibers. A method for measuring an absorption coefficient of a doped optical fiber may include: collecting, from a side of the doped optical fiber, an emission spectrum using two or more multimode fibers; and/or calculating the absorption coefficient form using the emission spectrum and McCumber theory.

A laser system with optical feedback, includes an optical-feedback-sensitive laser which emits, via an output optical fibre, a continuous, frequency-adjustable, propagating, source optical wave, known as the source wave; a resonant optical cavity coupled by means of optical feedback to the laser and configured to generate an intra-cavity wave, one fraction of which returns to the laser in the form of a counter-propagating optical wave; an electro-optic fibre modulator placed on the optical path between the laser and the resonant optical cavity, the electro-optic modulator being configured to generate a phase-shifted source wave by phase-shifting the source wave and, by phase-shifting the counter-propagating optical wave, to generate a phase-shifted counter-propagating wave, known as the feedback wave, which reaches the laser; a phase-control device for generating a control signal for the electro-optic modulator from an error signal representative of the relative phase between the source wave and the feedback wave, such as to cancel the relative phase between the source wave and the feedback wave.

Apparatuses, methods, and systems for detecting a substance are disclosed. One system includes a light source, an optical cavity, a cavity detector, and a processor. The light source generates a beam of electro-magnetic radiation, wherein a wavelength of the beam of electro-magnetic radiation is tuned to operate at multiple wavelengths. The optical cavity receives the beam of electro-magnetic radiation, wherein the physical characteristics of the cavity define a plurality of allowed axial-plus-transverse electro-magnetic radiation modes, wherein only a subset of the allowed axial-plus-transverse electro-magnetic radiation modes are excited when the optical cavity receives the beam of electro-magnetic radiation. The cavity detector senses electro-magnetic radiation emanating from the optical cavity. The processor operates to receive information relating to the sensed electro-magnetic radiation, and detects the substance within the optical cavity based on amplitude and/or phase of the sensed electro-magnetic radiation emanating from the optical cavity.

An embodiment of the present disclosure provides a spectrum inspecting apparatus. The apparatus includes a laser source; a focusing cylindrical lens configured to converge a light beam onto a sample; a light beam collecting device configured to collect a light beam signal, which is excited by the light beam, from the sample, so as to form a strip-shaped light spot; a slit configured to receive the collected light beam and couple it to downstream of a light path; a collimating device; a dispersing device configured to disperse the collected light beam so as to form a plurality of sub-beams having different wavelengths; an imaging device configured to image the sub-beams on the photon detector array respectively, wherein the light beam emitted from the laser source has a rectangular cross-section, the strip-shaped light spot impinges on the slit and its length is smaller than a length of the slit.

A non-destructive method for chemical imaging with 1 nm to 10 m spatial resolution (depending on the type of heat source) without sample preparation and in a non-contact manner. In one embodiment, a sample undergoes photo-thermal heating using an IR laser and the resulting increase in thermal emissions is measured with either an IR detector or a laser probe having a visible laser reflected from the sample. In another embodiment, the infrared laser is replaced with a focused electron or ion source while the thermal emission is collected in the same manner as with the infrared heating. The achievable spatial resolution of this embodiment is in the 1-50 nm range.

The application relates to a method of testing an item with a spectrally precise, artificial solar spectrum including wavelengths from 200 nm to 20 microns and it also relates to a solar spectrum simulator capable of producing a light spectrum including wavelengths from 200 nm to 20 microns. The simulator comprises: a) amplitude optimization software; b) a spectrum controller; c) an emitter controller; d) heat lamp/heater generation sources including: a xenon/infrared (IR) lamp and a blackbody radiator; e) laser generation sources including an ultraviolet (UV) laser source, a visible laser source, a near infrared (NIR) laser source, a short wavelength (SW) laser source, a medium wavelength (MW) laser source, a long wavelength (LW) laser source, and a quantum cascade laser source (QCL); f) a beam combiner; g) a beam profiler; h) a spectrometer; and i) a surface on which can be placed an item to be tested.

The application relates to a method of testing an item with a spectrally precise, artificial solar spectrum including wavelengths from 200 nm to 20 microns and it also relates to a solar spectrum simulator capable of producing a light spectrum including wavelengths from 200 nm to 20 microns. The simulator comprises: a) amplitude optimization software; b) a spectrum controller; c) an emitter controller; d) heat lamp/heater generation sources including: a xenon/infrared (IR) lamp and a blackbody radiator; e) laser generation sources including an ultraviolet (UV) laser source, a visible laser source, a near infrared (NIR) laser source, a short wavelength (SW) laser source, a medium wavelength (MW) laser source, a long wavelength (LW) laser source, and a quantum cascade laser source (QCL); f) a beam combiner; g) a beam profiler; h) a spectrometer; and i) a surface on which can be placed an item to be tested.

Disclosed herein is a spectroscopy device incorporating a mid-infrared laser. In one particular embodiment a spectroscopy device is provided including: a substrate; a single mode laser positioned on the substrate; a single mode detector positioned opposite to the single mode laser on the substrate. A gap is formed between the single mode laser and the single mode detector and a substance is positioned in the gap. The single mode laser is configured to output a tunable narrow wavelength of radiation towards the detector and when the single mode laser outputs a wavelength of radiation overlapping one of the substance's rotational-vibrational energy levels, the substance at least partially absorbs the radiation. The single mode detector is configured to measure the amount of narrow wavelength radiation that is not absorbed by the substance between the single mode detector and the single mode laser.