Abstract: In one aspect, the present invention provides techniques and apparatus for optical characterization of photonic devices and/or circuits. By way of example, the techniques can be used to identify damaged devices in photonic integrated circuits. In some embodiments, thermal imaging is employed as a diagnostic tool for characterizing the devices/circuits under investigation. For example, in one embodiment, integrated cascaded semiconductor amplifiers can be characterized using amplified spontaneous emission from one amplifier as a thermal modulation input to another amplifier. A thermoreflectance image of the second amplifier can reveal flaws, if present. Further, in some embodiments, thermal imaging in conjunction with a total energy model can be employed to characterize the elements of photonic circuits optically and/or to map the optical power distribution throughout the circuits.

Abstract: An embodiment of a method of performing thermoreflectance measurements with an imaging system comprises: reflecting radiation from a number of points in a sample in response to an illuminating radiation while a temperature modulation is applied to the sample; acquiring digital images of the reflected radiation after the reflected radiation passes through an aperture; and deriving a map of relative reflectivity of the sample based on the digital images. At least a portion of the illuminating radiation passes through at least a portion of the sample and is reflected at a change refractive index interface.

Abstract: In one aspect, the present invention provides techniques and apparatus for optical characterization of photonic devices and/or circuits. By way of example, the techniques can be used to identify damaged devices in photonic integrated circuits. In some embodiments, thermal imaging is employed as a diagnostic tool for characterizing the devices/circuits under investigation. For example, in one embodiment, integrated cascaded semiconductor amplifiers can be characterized using amplified spontaneous emission from one amplifier as a thermal modulation input to another amplifier. A thermoreflectance image of the second amplifier can reveal flaws, if present. Further, in some embodiments, thermal imaging in conjunction with a total energy model can be employed to characterize the elements of photonic circuits optically and/or to map the optical power distribution throughout the circuits.

Abstract: The invention is directed to systems and methods of digital signal processing and in particular to systems and methods for measurements of thermoreflectance signals, even when they are smaller than the code width of a digital detector used for detection. For example, in some embodiments, the number of measurements done is selected to be sufficiently large so as to obtain an uncertainty less than the code width of the detector. This allows for obtaining images having an enhanced temperature resolution. The invention is also directed to methods for predicting the uncertainty in measurement of the signal based on one or more noise variables associated with the detection process and the number of measurement iterations.

Abstract: The adsorption of poly(vinyl alcohol) (PVOH) from aqueous solution to hydrophobic solid-phase objects with varying chemical compositions, sizes, and geometries, is assessed as a new approach for surface modification. The effects of PVOH concentration, adsorption kinetics, PVOH molecular weight, adsorption temperature, solution ionic strength and stepwise deposition on wettability and adsorbed amounts were analyzed by water contact angle and X-ray Photoelectron Spectroscopy. PVOH adsorbs to solids significantly different than do other molecules. A much larger adsorbed amount and more dramatic improvement of wettability occurs compared to other molecules. The low solubility of PVOH, the strong tendency for it to crystallize at the solid/water interface and stabilization of the PVOH film by inter- and intra-molecular hydrogen bonding give additional driving forces for adsorption.