Apparatus and methods for probing a material as a function of depth using depth-dependent second harmonic generation
AssigneeVanderbilt University
InventorsJoy Garnett, Halina Krzyzanowska, Norman H. Tolk
Life of this patent
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Abstract
A method for non-invasively probing at least one physics property of a solid material. In one embodiment, the method has the steps of splitting a photon beam into a first photon beam and a second photon beam, exposing the solid material to the first photon beam to generate a coherent acoustic phonon wave in the solid material at time t, and exposing the solid material to the second photon beam at a time t+Δt, where t+Δt≥t, to generate corresponding second harmonic generation signals, where from the corresponding second harmonic generation signals, the at least one physics property of the solid material is determinable.
Claims37
A method for non-invasively probing at least one physics property of a solid material, wherein the solid material is in a form of a solid material layer having a first surface, a second, opposite surface, and a body portion therebetween the first surface and the second surface, wherein a layered structure is formed with a transducing layer deposited on the solid material layer, and wherein as formed, the layered structure has a first surface that is a surface of the transducing layer, a second, opposite surface that is a surface of the solid material layer, and an interface therebetween, comprising the steps of:
- (a) splitting a photon beam into a first photon beam and a second photon beam, wherein both of the first photon beam and the second photon beam have an identical wavelength that is same as that of the photon beam;
- (b) exposing the first surface of the layered structure to the first photon beam at time t with a first incident angle α1 to induce a coherent acoustic phonon wave in the transducing layer, which travels into the body portion of the solid material layer with a moving surface;
- (c) exposing the first surface of the layered structure to the second photon beam at time t+Δt, where t+Δt≥t, with a second incident angle α2 to produce a reflection beam comprising a first reflection beam and a second reflection beam, respectively, such that the first reflection beam comprises a first portion of the second photon beam that is reflected from the first surface of the layered structure, and the second reflection beam comprises a second portion of the second photon beam that is reflected from the moving surface of the coherent acoustic phonon wave traveling in the body portion of the solid material layer at a depth h, thereby causing an interference between the first reflection beam and the second reflection beam to generate corresponding second harmonic generation signals, wherein the second harmonic generation signals have a wavelength that is an half of the wavelength of the second photon beam;
- (d) spatially separating the produced reflection beam into a beam of the fundamental mode and a beam of the second harmonic generation signals, wherein the beam of the fundamental mode has a wavelength that is same as that of the second photon beam;
- (e) detecting the second harmonic generation signals;
- (f) measuring intensities of the second harmonic generation signals;
- and
- (g) determining the at least one physics property of the solid material at or around the depth h from the measured second harmonic generation intensities.
A method for non-invasively probing at least one physics property of a solid material, wherein the solid material is in a form of a solid material layer having a first surface, a second, opposite surface, and a body portion therebetween the first surface and the second surface, comprising the steps of:
- (a) splitting a photon beam into a first photon beam and a second photon beam, wherein both of the first photon beam and the second photon beam have an identical wavelength that is same as that of the photon beam;
- (b) with the first photon beam, generating a coherent acoustic phonon wave to travel in the body portion of the solid material with a moving surface at time t;
- (c) with the second photon beam, producing a reflection beam comprising a first reflection beam and a second reflection beam, respectively, such that the first reflection beam comprises a first portion of the second photon beam that is not reflected from the coherent acoustic phonon wave, and the second reflection beam comprises a second portion of the second photon beam that is reflected, at a time t+Δt, where t+Δt≥t, from the moving surface of the coherent acoustic phonon wave traveling in the body portion of the solid material layer at a depth h, thereby causing an interference between the first reflection beam and the second reflection beam to generate corresponding second harmonic generation signals, wherein the second harmonic generation signals have a wavelength that is an half of the wavelength of the second photon beam;
- (d) spatially separating the produced reflection beam into a beam of the fundamental mode and a beam of the second harmonic generation signals, wherein the beam of the fundamental mode has a wavelength that is same as that of the second photon beam;
- and
- (e) measuring intensities of the corresponding second harmonic generation signals, from which the at least one physics property of the solid material at or around the depth h is determinable.
A non-invasive optical probe for probing at least one physics property of a solid material, wherein the solid material is in a form of a solid material layer having a first surface, a second, opposite surface, and a body portion therebetween the first surface and the second surface, comprising:
- (a) a light source for emitting a light beam;
- (b) optical means for
- splitting the light beam into a first photon beam and a second photon beam wherein both of the first photon beam and the second photon beam have an identical wavelength that is same as that of the light beam;
- delivering the first photon beam to the solid material to generate a coherent acoustic phonon wave to travel in the body portion of the solid material with a moving surface at time t;
- delivering the second photon beam to the solid material to produce a reflection beam comprising a first reflection beam and a second reflection beam respectively, such that the first reflection beam comprises a first portion of the second photon beam that is not reflected from the coherent acoustic phonon wave, and the second reflection beam comprises a second portion of the second photon beam that is reflected, at a time t+Δt, where t+Δt≥t, from the moving surface of the coherent acoustic phonon wave traveling in the body portion of the solid material layer at a depth h, thereby causing an interference between the first reflection beam and the second reflection beam to generate corresponding second harmonic generation signals, wherein the second harmonic generation signals have a wavelength that is an half of the wavelength of the second photon beam;
- spatially separating the produced reflection beam into a beam of the fundamental mode and a beam of the second harmonic generation signals, wherein the beam of the fundamental mode has a wavelength that is same as that of the second photon beam;
- and
- (c) a detector for measuring intensities of the corresponding second harmonic generation signals,
- wherein the measured second harmonic generation signal intensities are associated with the at least one physics property of a solid material at or around the depth h.
A non-invasive optical probe for probing at least one physics property of a solid material, wherein the solid material has a first surface, a second, opposite surface, and a body portion therebetween the first surface and the second surface, comprising:
- (a) a laser source emitting a beam of pulses;
- and
- (b) an optical system configured to:
- split the beam of pulses into a first photon beam and a second photon beam, wherein both of the first photon beam and the second photon beam have an identical wavelength that is same as that of the beam of pulses;
- deliver the first photon beam to the solid material to generate a coherent acoustic phonon wave to travel in the body portion of the solid material with a moving surface at time t;
- deliver the second photon beam to the solid material to produce a reflection beam comprising a first reflection beam and a second reflection beam at a time t+Δt, where t+Δt≥t, such that the first reflection beam comprises a first portion of the second photon beam that is not reflected from the coherent acoustic phonon wave, and the second reflection beam comprises a second portion of the second photon beam that is reflected from the moving surface of the coherent acoustic phonon wave traveling in the body portion of the solid material at a depth h, thereby causing an interference between the first reflection beam and the second reflection beam to generate corresponding second harmonic generation signals, wherein the second harmonic generation signals have a wavelength that is an half of the wavelength of the second photon beam;
- spatially separate the produced reflection beam into a beam of the fundamental mode and a beam of the second harmonic generation signals, wherein the beam of the fundamental mode has a wavelength that is same as that of the second photon beam;
- and
- measure intensities of the corresponding second harmonic generation signals,
- wherein the measured second harmonic generation signal intensities are associated with the at least one physics property of the solid material at or around the depth h.
Dependencies are inferred from the claim text.