Abstract: According to examples, a channel checker optical time-domain reflectometer (OTDR) may include a laser source to emit a laser beam. An optical switch may be optically connected to the laser source to receive the laser beam and to selectively transmit the laser beam to a circulator that is optically connected to a device under test (DUT). A first coupler may be optically connected to a first photodiode and to the circulator. A second coupler may be optically connected to the first coupler, the optical switch, and a second photodiode.

Abstract: In some examples, parallel optics based optical time domain reflectometer acquisition may include a laser array operatively collimated to an optical fiber array to transmit, in parallel, a plurality of laser beams to optical fibers of the optical fiber array. A photodiode array may receive, in parallel, backscattered and reflected light from the optical fiber array. The photodiode array may determine, based on the backscattered and reflected light, properties of the optical fibers of the optical fiber array.

Abstract: In some examples, butt-coupling an avalanche photodiode may include coupling an optical fiber to an avalanche photodiode by butt-coupling the optical fiber to the avalanche photodiode. A face of the optical fiber may include a specified angle relative to and/or a specified distance from an active area of a chip associated with the avalanche photodiode. Further, the specified angle and/or the specified distance may be specified to minimize a tailing associated with an incident light beam from the optical fiber.

Abstract: In some examples, a temperature distribution sensor may include a laser source to emit a laser beam that is tunable over a wavelength range. The wavelength range may be less than a Raman bandwidth in a device under test (DUT), or of-the-order-of the Raman bandwidth in the DUT. A pulsed source may apply a pulse drive signal to the laser beam or to a modulator to modulate the laser beam that is to be injected into the DUT. A bandpass filter may be operatively disposed between the laser source and the DUT, and may be configured to an anti-Stokes wavelength that is narrower than the Raman bandwidth. A photodiode may be operatively disposed between the bandpass filter and the DUT to acquire, from the DUT, anti-Stokes optical time-domain reflectometer traces for two preset wavelengths of the laser beam to determine a temperature distribution for the DUT.

Abstract: According to examples, a channel checker optical time-domain reflectometer (OTDR) may include a laser source to emit a laser beam, An optical switch may be optically connected to the laser source to receive the laser beam and to selectively transmit the laser beam to a circulator that is optically connected to a device under test (DUT). A first coupler may be optically connected to a first photodiode and to the circulator, A second coupler may be optically connected to the first coupler, the optical switch, and a second photodiode.

Abstract: According to examples, an optical fiber-based sensing membrane may include at least one optical fiber, and a substrate. The at least one optical fiber may be integrated in the substrate. The optical fiber-based sensing membrane may include, based on a specified geometric pattern of the at least one optical fiber, an optical fiber-based sensing membrane layout. The substrate may include a thickness and a material property that are specified to ascertain, via the at least one optical fiber and based on the optical fiber-based sensing membrane layout, a thermal and/or a mechanical property associated with a device, or a radiation level associated with a device environment.

Abstract: According to examples, an optical fiber-based sensing membrane may include at least one optical fiber, and a substrate. The at least one optical fiber may be integrated in the substrate. The substrate may include a thickness and a material property that are specified to ascertain, via the at least one optical fiber and for a device that is contiguously engaged with a surface of the substrate, includes the substrate embedded in the device, or includes the surface of the substrate at a predetermined distance from the device, a thermal and/or a mechanical property associated with the device, or a radiation level associated with a device environment.

Abstract: According to examples, a Brillouin and Rayleigh distributed sensor may include a first laser source to emit a first laser beam, and a second laser source to emit a second laser beam. A photodiode may acquire a beat frequency between the two laser beams. The beat frequency may be used to maintain a predetermined offset frequency shift between the two laser beams. A modulator may modulate the first laser beam. The modulated first laser beam is to be injected into a device under test (DUT). A coherent receiver may acquire a backscattered signal from the DUT. The backscattered signal results from the modulated first laser beam injected into the DUT. The coherent receiver may use the second laser beam as a local oscillator to determine Brillouin and Rayleigh traces with respect to the DUT based on the predetermined offset frequency shift.

Abstract: In some examples, a temperature distribution sensor may include a laser source to emit a laser beam that is tunable over a wavelength range. The wavelength range may be less than a Raman bandwidth in a device under test (DUT), or of-the-order-of the Raman bandwidth in the DUT. A pulsed source may apply a pulse drive signal to the laser beam or to a modulator to modulate the laser beam that is to be injected into the DUT. A bandpass filter may be operatively disposed between the laser source and the DUT, and may be configured to an anti-Stokes wavelength that is narrower than the Raman bandwidth. A photodiode may be operatively disposed between the bandpass filter and the DUT to acquire, from the DUT, anti-Stokes optical time-domain reflectometer traces for two preset wavelengths of the laser beam to determine a temperature distribution for the DUT.

Abstract: In some examples, a temperature distribution sensor may include a laser source to emit a laser beam that is tunable over a wavelength range. The wavelength range may be less than a Raman bandwidth in a device under test (DUT), or of-the-order-of the Raman bandwidth in the DUT. A pulsed source may apply a pulse drive signal to the laser beam or to a modulator to modulate the laser beam that is to be injected into the DUT. A bandpass filter may be operatively disposed between the laser source and the DUT, and may be configured to an anti-Stokes wavelength that is narrower than the Raman bandwidth. A photodiode may be operatively disposed between the bandpass filter and the DUT to acquire, from the DUT, anti-Stokes optical time-domain reflectometer traces for two preset wavelengths of the laser beam to determine a temperature distribution for the DUT.

Abstract: In some examples, parallel optics based optical time domain reflectometer acquisition may include a laser array operatively collimated to an optical fiber array to transmit, in parallel, a plurality of laser beams to optical fibers of the optical fiber array. A photodiode array may receive, in parallel, backscattered and reflected light from the optical fiber array. The photodiode array may determine, based on the backscattered and reflected light, properties of the optical fibers of the optical fiber array.

Abstract: In some examples, parallel optics based optical time domain reflectometer acquisition may include a laser array operatively collimated to an optical fiber array to transmit, in parallel, a plurality of laser beams to optical fibers of the optical fiber array. A photodiode array may receive, in parallel, backscattered and reflected light from the optical fiber array. The photodiode array may determine, based on the backscattered and reflected light, properties of the optical fibers of the optical fiber array.

Abstract: According to examples, a Brillouin and Rayleigh distributed sensor may include a first laser source to emit a first laser beam, and a second laser source to emit a second laser beam. A photodiode may acquire a beat frequency between the two laser beams. The beat frequency may be used to maintain a predetermined offset frequency shift between the two laser beams. A modulator may modulate the first laser beam. The modulated first laser beam is to be injected into a device under test (DUT). A coherent receiver may acquire a backscattered signal from the DUT. The backscattered signal results from the modulated first laser beam injected into the DUT. The coherent receiver may use the second laser beam as a local oscillator to determine Brillouin and Rayleigh traces with respect to the DUT based on the predetermined offset frequency shift.

Abstract: In some examples, parallel optics based optical time domain reflectometer acquisition may include a laser array operatively collimated to an optical fiber array to transmit, in parallel, a plurality of laser beams to optical fibers of the optical fiber array. A photodiode array may receive, in parallel, backscattered and reflected light from the optical fiber array. The photodiode array may determine, based on the backscattered and reflected light, properties of the optical fibers of the optical fiber array.

Abstract: According to examples, a Brillouin and Rayleigh distributed sensor may include a first laser source to emit a first laser beam, and a second laser source to emit a second laser beam. A photodiode may acquire a beat frequency between the two laser beams. The beat frequency may be used to maintain a predetermined offset frequency shift between the two laser beams. A modulator may modulate the first laser beam. The modulated first laser beam is to be injected into a device under test (DUT), A coherent receiver may acquire a backscattered signal from the DUT. The backscattered signal results from the modulated first laser beam injected into the DUT. The coherent receiver may use the second laser beam as a local oscillator to determine Brillouin and Rayleigh traces with respect to the DUT based on the predetermined offset frequency shift.

Abstract: In some examples, a temperature distribution sensor may include a laser source to emit a laser beam that is tunable over a wavelength range. The wavelength range may be less than a Raman bandwidth in a device under test (DUT), or of-the-order-of the Raman bandwidth in the DUT. A pulsed source may apply a pulse drive signal to the laser beam or to a modulator to modulate the laser beam that is to be injected into the DUT. A bandpass filter may be operatively disposed between the laser source and the DUT, and may be configured to an anti-Stokes wavelength that is narrower than the Raman bandwidth. A photodiode may be operatively disposed between the bandpass filter and the DUT to acquire, from the DUT, anti-Stokes optical time-domain reflectometer traces for two preset wavelengths of the laser beam to determine a temperature distribution for the DUT.

Abstract: In some examples, a temperature distribution sensor may include a laser source to emit a laser beam that is tunable over a wavelength range. The wavelength range may be less than a Raman bandwidth in a device under test (DUT), or of-the-order-of the Raman bandwidth in the DUT. A pulsed source may apply a pulse drive signal to the laser beam or to a modulator to modulate the laser beam that is to be injected into the DUT. A bandpass filter may be operatively disposed between the laser source and the DUT, and may be configured to an anti-Stokes wavelength that is narrower than the Raman bandwidth. A photodiode may be operatively disposed between the bandpass filter and the DUT to acquire, from the DUT, anti-Stokes optical time-domain reflectometer traces for two preset wavelengths of the laser beam to determine a temperature distribution for the DUT.

Abstract: According to examples, a temperature or strain distribution sensor may include a photodiode to acquire a beat frequency between a first laser beam and a second laser beam. A modulator may modulate the first laser beam that is to be injected into a device under test (DUT). A coherent receiver may acquire a backscattered signal from the DUT, and use the second laser beam as a local oscillator to determine a Brillouin trace with respect to the DUT. The Brillouin trace may be used to determine a Brillouin frequency shift and a Brillouin power for the DUT to implement an absolute referencing of a Rayleigh reference trace. The coherent receiver may determine, relative to the Rayleigh reference trace, a further Brillouin frequency shift and a Rayleigh frequency shift to determine a temperature or a strain associated with the DUT.

Abstract: In some examples, a temperature distribution sensor may include a laser source to emit a laser beam that is tunable over a wavelength range. The wavelength range may be less than a Raman bandwidth in a device under test (DUT), or of-the-order-of the Raman bandwidth in the DUT. A pulsed source may apply a pulse drive signal to the laser beam or to a modulator to modulate the laser beam that is to be injected into the DUT. A bandpass filter may be operatively disposed between the laser source and the DUT, and may be configured to an anti-Stokes wavelength that is narrower than the Raman bandwidth. A photodiode may be operatively disposed between the bandpass filter and the DUT to acquire, from the DUT, anti-Stokes optical time-domain reflectometer traces for two preset wavelengths of the laser beam to determine a temperature distribution for the DUT.

Abstract: According to examples, a Brillouin and Rayleigh distributed sensor may include a first laser source to emit a first laser beam, and a second laser source to emit a second laser beam. A photodiode may acquire a beat frequency between the two laser beams. The beat frequency may be used to maintain a predetermined offset frequency shift between the two laser beams. A modulator may modulate the first laser beam. The modulated first laser beam is to be injected into a device under test (DUT), A coherent receiver may acquire a backscattered signal from the DUT. The backscattered signal results from the modulated first laser beam injected into the DUT. The coherent receiver may use the second laser beam as a local oscillator to determine Brillouin and Rayleigh traces with respect to the DUT based on the predetermined offset frequency shift.