Abstract: Performing modulation spectroscopy by directing a probe beam and a pump beam at a strained semiconductor sample, modulating the pump beam, and reflecting the probe beam into a detector. The detector produces a direct current signal proportional to reflectance R of the probe beam and an alternating current signal proportional to the modulation of the reflectance ?R of the probe beam. Both R and ?R are measured at a multiplicity of probe beam photon energies, to provide a spectrum having at least one line shape. The spectrum is analyzed to measure energy differences between interband electronic transitions of the sample, and the strain of the sample is determined from the energy differences.

Abstract: An optical measurement apparatus and method a method for performing modulation spectroscopy measurement of a sample comprising: delivering an incident probe beam to a sample at a known spot; modulating reflectance of the probe beam with a pump beam which periodically forms a pump beam spot on the sample coincident with the probe beam spot; and monitoring a reflected probe beam with a detector: wherein the incident probe and pump beams are collinear; and wherein the incident beams are directed to be collinear by reflecting a beam from a facet of an optical waveguide transmitting the other beam.

Abstract: An optical modulation spectroscopy system comprises a probe beam source and components for directing the probe beam at a sample. It also may comprise a modulated pump beam source and components for directing a modulated pump beam at the sample. A dispersive system may disperse the reflected probe beam into constituent wavelengths to provide dispersed beams. A detector array may detect multiple dispersed reflected probe beams and processes a signal corresponding to each. Thus, measurement may be multiplexed for very fast performance.

Abstract: An optical modulation spectroscopy system comprises a probe beam source and components for directing the probe beam at a sample. It also may comprise a modulated pump beam source and components for directing a modulated pump beam at the sample. A dispersive system may disperse the reflected probe beam into constituent wavelengths to provide dispersed beams. A detector array may detect multiple dispersed reflected probe beams and processes a signal corresponding to each. Thus, measurement may be multiplexed for very fast performance.

Abstract: An optical measurement apparatus and method a method for performing modulation spectroscopy measurement of a sample comprising: delivering an incident probe beam to a sample at a known spot; modulating reflectance of the probe beam with a pump beam which periodically forms a pump beam spot on the sample coincident with the probe beam spot; and monitoring a reflected probe beam with a detector: wherein the incident probe and pump beams are collinear; and wherein the incident beams are directed to be collinear by reflecting a beam from a facet of an optical waveguide transmitting the other beam.

Abstract: In one embodiment, a modulation spectroscopy method comprises the steps of directing a probe beam and a pump beam at a sample, modulating the pump beam, and the probe beam is reflected from the sample into a detector. The sample may include a strained semiconductor. The detector may produce as output an electrical signal which comprises a large d.c. signal proportional to reflectance R of the probe beam and a small a.c. modulated signal at the modulation frequency proportional to the modulation of the reflectance ?R of the probe beam. Both the reflectance R of the probe beam and the modulation of the reflectance ?R of the probe beam are measured at a multiplicity of probe beam photon energies arising from different wavelengths of the probe beam, to provide a photoreflectance spectrum comprising at least one photoreflectance lineshape.

Abstract: A modulation spectroscopy system (1) directs a probe beam (11) onto a sample (10), the reflected probe beam being collected by a collector (7) and processed by a detector (8). A pump beam generated by a source (4, 5) directs a pump beam (13) onto the sample at the same spot as the probe beam. However, it also switches the pump beam via a path (14) onto an adjacent location not overlapping the probe spot. This is referred to as spatial modulation. A cylindrical lens (16) in the collection subsystem (7) collects reflected light including luminescence from both pump beam spots simultaneously, so that the luminescence becomes a d.c. signal which can be easily eliminated, including means from the modulator for varying pump beam intensities and positions. This provides means to reject the unwanted background luminescence signal as well as improvement to the signal to noise ratio.

Abstract: A planar waveguide (1) comprises a guiding layer (4) with densified cores (4, 5) for propagation of radiation. The cores (4, 5) are formed by selectively exposing the guiding layer (4) to UV at 222 nm with an intensity of 75 mW/cm?2 at the surface. The guiding layer material comprises components in the methacrylate functional group. There is no need for use of photo-initiator additives in the guiding layer material.

Abstract: A process of forming a material such as a waveguide with at least two regions of differing refractive indices comprising the steps of: (a) providing an amount of a gelable composition comprising at least one gelable component in a desired form; (b) exposing the gelable composition to conditions which partially gel the gelable composition so that an amount of ungelled material remains; (c) exposing at least one discrete region of the partially gelled product of step (b) to conditions which induce more complete gelation of the partially gelled gelable composition so that more of the ungelled material is incorporated into the gel structure in the exposed regions than in non-exposed regions; and (d) removing material not incorporated in the gel structure at least from the non-exposed region. A second component may additionally be provided, the second component being selected to impart a higher or lower refractive index to that part of the material in which it is incorporated.