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In this paper, we propose a sensitivity-enhanced thermoreflectance microscopy (TRM) system employing an electronic auto-balancing photoreceiver for effective thermal fault localization through a Si substrate. The proposed system in the auto-balanced detection not only improves the system signal-to-noise ratio (SNR) by approximately five times compared to that achievable via normal detection but also mitigates the inherent system noise, such as pseudothermoreflectance signals, by using the optical zooming. Moreover, temperature variations as small as ~47 mK were detectable under the measurement conditions employed in this paper. Finally, we experimentally demonstrated clear localization of a thermal fault, which was dimly visible in the normal backside detection results, in an optical zoomed thermal image. [ABSTRACT FROM AUTHOR]

We report a compact all-optical side-firing probe directly ablated on a mode-expanded hybrid fiber end using a high-precision femtosecond laser processing technique. A segment of coreless silica fiber was adopted to achieve a large beam size and manipulation of the far field divergence angle. The radiating beam properties of the side-firing tip have been experimentally investigated and compared with numerical simulations. [ABSTRACT FROM PUBLISHER]

A simple and compact lensed dual-fiber probe having high collection efficiency for fluorescence signal is demonstrated. A lensed dual-fiber probe, composed of two parallel fibers and a common focusing lens, was simply implemented by the electric arc discharge method. The performance of the proposed probe was evaluated experimentally by measuring the reflection powers and fluorescence spectra of well-known targets and a fresh ginkgo leaf. The experimental result shows that the proposed probe provides a six-fold increase in the collection efficiency compared to measurements without the lens. In addition, the signal collection occurs very close to the probe surface with a suitably localized depth. [ABSTRACT FROM PUBLISHER]