Abstract: In one embodiment, an apparatus includes a needle that includes a substantially cylindrical shaft and a lumen, which includes a hollow space located within the shaft. The shaft includes a tip located at an end of the shaft, where the tip includes an opening. The apparatus also includes an optical fiber that includes an end face. The end face and at least a portion of the optical fiber are located within the lumen. The optical fiber is configured to transmit a pump-Stokes beam of light along the optical fiber toward the tip of the needle and to the end face, where the pump-Stokes beam is emitted from the end face and directed to a sample. The apparatus further includes a catheter that includes a catheter connector and a catheter tube having a substantially cylindrical shape, where the catheter tube surrounds at least a portion of the needle shaft.

Abstract: In one embodiment, an apparatus includes a catheter insert that includes a catheter connector and a sheath having a substantially cylindrical shape. The catheter insert is configured to be coupled to a catheter that includes a mating connector and a catheter tube, where at least a portion of the sheath is configured to be inserted into the catheter tube, and the catheter connector is configured to be connected to the mating connector. The apparatus also includes an optical fiber that includes an end face, where at least a portion of the optical fiber is contained within the sheath. The optical fiber is configured to transmit a pump-Stokes beam of light along the optical fiber to the end face, where the pump-Stokes beam is emitted from the end face and directed to a sample.

Abstract: In one embodiment, an apparatus includes a needle that includes a substantially cylindrical shaft and a lumen. The lumen includes a hollow space located within the shaft, and the shaft includes a tip located at an end of the shaft, where the tip includes an opening. The apparatus also includes an optical fiber that includes an end face, where the end face and at least a portion of the optical fiber are located within the lumen. The optical fiber is configured to transmit a pump-Stokes beam of light along the optical fiber toward the tip of the needle and to the end face, where the pump-Stokes beam is emitted from the end face and directed through the opening of the needle along a propagation direction that is at an angle with respect to a central axis of the needle.

Abstract: In one embodiment, an apparatus includes a needle that includes a substantially cylindrical shaft and a lumen. The lumen includes a hollow space located within the shaft, and the shaft includes a tip located at an end of the shaft. The apparatus also includes an optical fiber that includes an end face, where the end face and at least a portion of the optical fiber are located within the lumen. The optical fiber is configured to transmit a pump-Stokes beam of light along the optical fiber toward the tip of the needle and to the end face, where the pump-Stokes beam is emitted from the end face and directed to a sample located in the lumen. The pump-Stokes beam is configured to produce a Raman signal by coherent Raman scattering of the pump-Stokes beam while propagating through the sample.

Abstract: In one embodiment, an apparatus includes a needle that includes a substantially cylindrical shaft and a lumen. The lumen includes a hollow space located within the shaft, and the shaft includes a tip located at an end of the shaft, where the tip includes an opening. The apparatus also includes an optical fiber that includes an end face, where the end face and at least a portion of the optical fiber are located within the lumen. The optical fiber is configured to transmit a pump-Stokes beam of light along the optical fiber toward the tip of the needle and to the end face, where the pump-Stokes beam is emitted from the end face and directed through the opening of the needle to a sample.

Abstract: In one embodiment, an apparatus includes a needle that includes a substantially cylindrical shaft that includes a tip located at a distal end of the shaft, where the tip includes an opening. The apparatus also includes an optical waveguide located within the shaft of the needle. The optical waveguide is configured to (i) receive a pump-Stokes beam of light emitted from an end face of an optical fiber, where the optical-fiber end face is located at a proximal end of the shaft opposite the distal end and (ii) convey the pump-Stokes beam along the optical waveguide to the tip of the needle, where the pump-Stokes beam is emitted from the optical waveguide and directed through the opening of the needle to a sample.

Abstract: In one embodiment, a system includes a pump light source configured to produce a pump beam of light at a pump frequency and a Stokes light source configured to produce a Stokes beam of light at a Stokes frequency, where the pump and Stokes frequencies are offset by a frequency offset ?. The system further includes a photonic integrated circuit (PIC) that includes multiple optical waveguides configured to: direct the pump and Stokes beams of light to a sample; receive a Raman signal produced by coherent Raman scattering of the pump and Stokes beams of light at the sample; and direct the Raman signal to an optical receiver. The optical receiver is configured to detect the Raman signal. The optical receiver includes a probe light source configured to produce a probe beam of light at a probe frequency, an optical detector, and an electronic circuit.