High-pulse energy supercontinuum laser for high-resolution spectroscopic photoacoustic imaging of lipids in the 1650-1850 nm region

Abstract

We propose a cost-effective high-pulse energy supercontinuum (SC) source based on a telecom range diode laser-based amplifier and a few meters of standard single-mode optical fiber, with a pulse energy density as high as ~25 nJ/nm in the 1650-1850 nm regime (factor >3 times higher than any SC source ever used in this wavelength range). We demonstrate how such an SC source combined with a tunable filter allows high-resolution spectroscopic photoacoustic imaging and the spectroscopy of lipids in the first overtone transition band of C-H bonds (1650-1850 nm). We show the successful discrimination of two different lipids (cholesterol and lipid in adipose tissue) and the photoacoustic cross-sectional scan of lipid-rich adipose tissue at three different locations. The proposed high-pulse energy SC laser paves a new direction towards compact, broadband and cost-effective source for spectroscopic photoacoustic imaging.

Amplitude noise and coherence degradation of femtosecond supercontinuum generation in all-normal-dispersion fibers

“…Despite these obstacles, fs-pumped ANDi SC generation has received significant attention because of its ability to generate temporally coherent SC pulses; a feature that is unachievable in the anomalous dispersion regime. This gives such systems potential in a range of fields including optical coherence tomography (OCT), optical metrology, photo-acoustic imaging, and spectroscopy [6][7][8][9][10][11].…”

Towards an all-fiber system for detection and monitoring of ammonia

“…After cleaving, the facet of the fiber was inserted in a ferrule to allow only a small part to extrude out, as shown in figures 1(i) & (ii). One end of the HC-PBG is mechanically spliced to the SC laser source with a ferrule-mating sleeve (details of the SC laser are reported in our previous study 22 ). The connectorization is done by carefully placing the cleaved fiber ends into the ferrule, and glued at the end to provide mechanical strength, the ferrules are then matted with a mating sleeve and both procedures were performed under an optical microscope for better precission.…”

Multispectral photoacoustic sensing for accurate glucose monitoring using a supercontinuum laser

“…The pulse energy of the SC laser at 30 kHz pulse repetition rate is 13.3 μJ over a bandwidth of 400 nm (1500-1900 nm). The detailed configuration of the SC laser source is described in our previous study [14]. The output from the SC laser source is collimated using an achromatic lens (L1) (RC02FC-P01, Thorlabs).…”

“…Figure 1 shows the measured spectral characteristics of two different analytes (distilled water and glucose) indicating the well-differentiated absorption peaks between the two. The spectral difference between the two analytes can be attributed to the overtone and combination bands of C─H and O─H bonds [14]. In vitro PA studies on aqueous glucose within this spectral region have been performed using commercially available monochromatic laser sources mainly at 1550 nm [13].…”