The disclosed technology generally relates to characterization of semiconductor structures, and more particularly to optical characterization of high-k dielectric materials. A method includes providing a semiconductor structure comprising a semiconductor and a high-k dielectric layer formed over the semiconductor, wherein the dielectric layer has electron traps formed therein. The method additionally includes at least partially transmitting an incident light having an incident energy through the high-k dielectric layer and at least partially absorbing the incident light in the semiconductor. The method additionally includes measuring a nonlinear optical spectrum resulting from the light having the energy different from the incident energy, the nonlinear optical spectrum having a first region and a second region, wherein the first region changes at a different rate in intensity compared to the second region. The method further includes determining from the nonlinear optical spectrum one or both of a first time constant from the first region and a second time constant from the second region, and determining a trap density in the high-k dielectric layer based on the one or both of the first time constant and the second time constant.

Surface sensing methods for imaging a scanned surface of a sample via sum-frequency vibrational spectroscopy are disclosed herein. The methods include exposing a sampled location of the scanned surface to a visible light beam and exposing the sampled location to a tunable infrared beam such that the tunable infrared beam is at least partially coincident with the visible light beam. The methods also include varying a frequency of the tunable infrared beam an inducing optical resonance within an imaged structure that extends at least partially within the sampled location. The methods further include receiving at least a portion of an emitted light beam from the sampled location and scanning the visible light beam and the runnable infrared beam across the scanned portion of the scanned surface. The methods also include generating an image of the scanned portion of the scanned surface based upon the receiving and the scanning.

Various approaches to can be used to interrogate a surface such as a surface of a layered semiconductor structure on a semiconductor wafer. Certain approaches employ Second Harmonic Generation and in some cases may utilize pump and probe radiation. Other approaches involve determining current flow from a sample illuminated with radiation.

Embodiments disclosed include methods and apparatus for Fluorescent Enhanced Photothermal Infrared (FE-PTIR) spectroscopy and chemical imaging, which enables high sensitivity and high spatial resolution measurements of IR absorption with simultaneous confocal fluorescence imaging. In various embodiments, the FE-PTIR technique utilizes combined/simultaneous OPTIR and fluorescence imaging that provides significant improvements and benefits compared to previous work by simultaneous detection of both IR absorption and confocal fluorescence using the same optical detector at the same time.

Various approaches to can be used to interrogate a surface such as a surface of a layered semiconductor structure on a semiconductor wafer. Certain approaches employ Second Harmonic Generation and in some cases may utilize pump and probe radiation. Other approaches involve determining current flow from a sample illuminated with radiation.

Disclosed is a system and method for interrogating a photo-responsive material, such as for authentication purposes, utilizing a light source to illuminate a photo-responsive material, a detector to capture an emission from the photo-responsive material, and a processor to receive a response from the detector while the photo-responsive material is being illuminated after a maximum response has been received, then measuring a change in the received response.

A pressure cell for sum frequency generation spectroscopy includes: a metal pressure chamber; a heating stage that heats a liquid sample; an ultrasonic stage that emulsifies the liquid sample; a chamber pump that pressurizes an interior of the metal pressure chamber; and a controller that controls the chamber pump, the ultrasonic stage, and the heating stage to control a pressure of the interior of the metal pressure chamber, an emulsification of the liquid sample, and a temperature of the liquid sample, respectively. The metal pressure chamber includes: a liquid sample holder that retains the liquid sample; a removable lid that seals against a base; a window in the removable lid; a sample inlet that flows the liquid sample from an exterior of the metal pressure chamber to the liquid sample holder at a predetermined flow rate; and a sample outlet.

Disclosed is a hand-held optical apparatus and method for using the apparatus to activate and detect optical emissive materials as part of a safety interlock system. Typically, the hand-held optical apparatus will include one or more light sources capable of emitting at least one wavelength of light towards an optical emissive material, a light detector capable of detecting a response from the optical emissive material, and control circuitry configured to cause at least one of the one or more light sources to emit the at least one wavelength at a power density less than a predetermined threshold, receive a signal from the light detector representing a detected response, and repeat until the microprocessor determines the detected response matches an expected response.

Disclosed herein is an all-fiber, easy to use, wavelength tunable, ultrafast laser based on soliton self-frequency-shifting in an Er-doped polarization-maintaining very large mode area (PM VLMA) fiber. The ultrafast laser system may include an all polarization-maintaining (PM) fiber mode-locked seed laser with a pre-amplifier; a Raman laser including a cascaded Raman resonator and an ytterbium (Yb) fiber laser cavity; an amplifier core-pumped by the Raman laser, the amplifier including an erbium (Er) doped polarization maintaining very large mode area (PM Er VLMA) optical fiber and a passive PM VLMA fiber following the PM Er VLMA, the passive PM VLMA for supporting a spectral shift to a longer wavelength.

Various approaches can be used to interrogate a surface such as a surface of a layered semiconductor structure on a semiconductor wafer. Certain approaches employ Second Harmonic Generation and in some cases may utilize pump and probe radiation. Other approaches involve determining current flow from a sample illuminated with radiation. Decay constants can be measured to provide information regarding the sample. Additionally, electric and/or magnetic field biases can be applied to the sample to provide additional information.