Over the last two decades solid immersion objectives have been developed for various applications, offering the opportunity to achieve a higher resolution than is possible for conventional air objective lenses. For semiconductor applications hemispherical solid immersion lenses (SILs), incorporating tips fabricated in semiconductor materials with a high refractive index (up to n = 3:5 for silicon, for example) are commonly used. With such high refractive index materials it is possible to design an objective with a numerical aperture of NA = 3:2. An apochromatic color correction is mandatory if a broad spectral range from λ = 1200 nm to λ = 2000 nm is required. It is well known that glasses with anomalous partial dispersion must be used to realize apochromatic color correction. It will be shown that the anomalous partial dispersions of some glasses in the IR range differ from the known behavior in the visible region. Therefore, glass selection plays a significant role for the design of a high NA broadband IR objective and will be discussed. Monte Carlo tolerance analysis shows that even with state of the art manufacturing capabilities the tolerance induced aberrations of an objective with NA = 3:2 will lead to a dramatic loss of image performance, indicated by a significant drop in the Strehl-ratio. This becomes even worse when the interface of the exchangeable hemispherical SIL tip with the main objective is considered. With the aim to manufacture such objectives within a stable production process it makes no sense to overload the requirements regarding the NA. Therefore, due to manufacturing issues the numerical aperture of this objective has been restricted to NA = 2:9. Wave front measurements of the manufactured objectives shows Strehl-ratios of SR > 97 % which guarantees a diffraction limited resolution.
We report on the photoresponse mapping of nanowire superconducting single-photon detectors using a focal spot
significantly smaller than the device area (10 μm x 10 μm). Using a solid immersion lens we achieve a spot size of 320
nm full-width half maximum onto the device at 470 nm wavelength. We compare the response maps of two devices: the
higher detection efficiency device gives a uniform response whereas the lower detection efficiency device is limited by a
single defect or constriction. A second optical setup is used to simultaneously image and measure the photoresponse of
the lower detection efficiency device, allowing the constriction location to be pinpointed.
Solid immersion lens (SIL) microscopy combines the advantages of conventional microscopy with those of near-field techniques, and is being increasingly adopted across a diverse range of technologies and applications. A comprehensive overview of the state-of-the-art in this rapidly expanding subject is therefore increasingly relevant. Important benefits are enabled by SIL-focusing, including an improved lateral and axial spatial profiling resolution when a SIL is used in laser-scanning microscopy or excitation, and an improved collection efficiency when a SIL is used in a light-collection mode, for example in fluorescence micro-spectroscopy. These advantages arise from the increase in numerical aperture (NA) that is provided by a SIL. Other SIL-enhanced improvements, for example spherical-aberration-free sub-surface imaging, are a fundamental consequence of the aplanatic imaging condition that results from the spherical geometry of the SIL. Beginning with an introduction to the theory of SIL imaging, the unique properties of SILs are exposed to provide advantages in applications involving the interrogation of photonic and electronic nanostructures. Such applications range from the sub-surface examination of the complex three-dimensional microstructures fabricated in silicon integrated circuits, to quantum photoluminescence and transmission measurements in semiconductor quantum dot nanostructures.
We report the use of electric field induced second harmonic generation to probe electrical signals in a CMOS chip. The second harmonic of incident 2.3μm illumination provided by a femtosecond optical parametric oscillator was measured and shown to depend quadratically on both optical intensity and on the applied DC electric field. By using a near infrared photomultiplier tube it was possible to monitor directly the electrical waveform in the chip on the oscilloscope.
This paper reports the imaging of a silicon flip-chip with high resolution by detection of the photocurrent generated by the two-photon absorption of 1530nm light from a femtosecond Er:fiber laser. High resolution imaging was made possible by the inclusion of a silicon solid immersion lens, which increased the numerical aperture of the microscope. Using this technique, features on a sub-micron scale are clearly resolvable with excellent contrast, and the resolution of the system was found to be 325nm.
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