Fiber-connectorized ultrafast-laser-inscribed K-band integrated optics beam combiner for the CHARA telescope array.

A fiber-connectorized K-band integrated-optics two-telescope beam combiner was developed for long-baseline interferometry at the CHARA telescope array utilizing the ultrafast laser inscription (ULI) technique. Single-mode waveguide insertion losses were measured to be ∼1.1d B over the 2-2.3 µm window. The development of asymmetric directional couplers enabled the construction of a beam combiner that includes a 50:50 coupler for interferometric combination and two ∼75:25 couplers for photometric calibration. The visibility of the bare beam combiner was measured at 87% and then at 82% after fiber-connectorization by optimizing the input polarization. These results indicate that ULI technique can fabricate efficient fiber-connectorized K-band beam combiners for astronomical purposes.

Noncontact stimulation of the cavernous nerves in the rat prostate using a tunable-wavelength thulium fiber laser.

BACKGROUND AND PURPOSE: Laser nerve stimulation has recently been studied in neuroscience as an alternative to electrical stimulation. Its advantages include noncontact stimulation, better spatial selectivity, and elimination of electrical stimulation artifacts. This study explored laser stimulation of the rat cavernous nerves as a potential alternative to electrical nerve mapping during nerve-sparing radical prostatectomy. MATERIALS AND METHODS: The cavernous nerves were surgically exposed in 10 male rats. A thulium fiber laser stimulated the nerves, with a wavelength of 1870 nm, pulse energy of 7.5 mJ, radiant exposure of 1 J/cm2, pulse duration of 2.5 msec, pulse rate of 10 Hz, and 1-mm laser spot diameter, for a stimulation time of 60 sec. RESULTS AND CONCLUSION: A significant increase in the intracavernosal pressure was detected on laser stimulation, with pressure returning to baseline values after stimulation ceased. This study demonstrates the feasibility of noncontact stimulation of the cavernous nerves using near-infrared laser radiation.

Laser stimulation of the cavernous nerves in the rat prostate, in vivo: optimization of wavelength, pulse energy, and pulse repetition rate.

The cavernous nerves on the prostate surface are responsible for erectile function. Improved diagnostic techniques are necessary for identification of the nerves during prostate cancer surgery and preservation of sexual function after surgery. Electrical mapping of the nerves has been used as an intra-operative tool during prostate surgery, but it has proven inconsistent and unreliable. Non-contact optical stimulation of the cavernous nerves in the rat prostate has recently been demonstrated as a potential alternative to electrical nerve stimulation. The purpose of this study is to optimize the laser parameters to provide the maximum intracavernosal pressure response after optical nerve stimulation in the rat prostate. Optimal laser nerve stimulation parameters provided comparable response to electrical nerve stimulation. Optical nerve stimulation may represent a potential intra-operative diagnostic technique for use in laparoscopic and robotic nerve-sparing prostate cancer surgery.

Noninvasive thermal coagulation of deep subsurface tissue structures using a laser probe with integrated contact cooling.

Cooling methods are used during cosmetic laser surgery to preserve a superficial layer of the skin surface. This study investigates contact cooling for sparing a deeper layer of the tissue surface during laser irradiation of subsurface tissues, with the goal of developing noninvasive laser therapy applications beyond cosmetic surgery. A laser probe was designed and tested for simultaneous laser irradiation and contact cooling of liver tissue, ex vivo. Gross and histologic examination was used to quantify thermal lesion dimensions. Liver lesions of 5.8-mm-diameter were created, while preserving the tissue surface to a depth of 1.5 mm. In vivo animal studies are planned to optimize the laser and cooling parameters for potential clinical applications.