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AssigneeThe Provost, Fellows and Scholars ofthe college of the Holy and Undivided Trinity of Queen Elizabeth
InventorsWei-Hua Guo, John Francis Donegan, Ann Louise Bradley, Michael Andrew Lynch, Torsten Krug
Estimating the term…
Apparatus for determining the pulse width of ultra-short light pulses of an input repetitive light pulse signal comprises a two-photon absorption detector (2) in the form of a microcavity (3) having an active region (4) located between top and bottom distributed Bragg reflectors (5,6). An optical fibre cable 16 directs the input light pulse signal combined with a reference repetitive light pulse signal normal to an incident surface (8) of the detector (2). The input light pulse signal is split in a polarisation light splitter (19) to form the reference light pulse signal which is passed through a delay line (23) to a polarisation light combiner (20) to be combined with the input light pulse signal, and directed at the incident surface (8) by the optical fibre cable (16). The delay line (23) is operated for alternately bringing the respective light pulses of the input and reference light pulse signals into and out of phase with each other to produce a pulsed photocurrent in the microcavity (3). A monitoring circuit (14) monitors the pulsed photocurrent, and the pulse width of the light pulses is determined as the full width half maximum of the pulsed photocurrent trace. By varying the angle of incidence at which the input and reference light pulse signals are incident on the incident surface (8), the apparatus is tuneable to input light pulse signals of different wavelengths within a predetermined range of wavelengths.
1-194. (canceled)
Apparatus for determining the pulse width of light pulses of an input repetitive light pulse signal of repeating ultra-short light pulses, the apparatus comprising a two-photon absorption photodetector, the two-photon absorption photodetector being provided in the form of a microcavity comprising an active region and spaced apart first and second reflecting means between which the active region is located, and within which light resonates to produce a photocurrent as a result of the two-photon absorption effect, the active region and the first and second reflecting means being adapted so that the resonating lifetime of light in the microcavity is less than the pulse width of the light pulses, the pulse width of which is to be determined, a light directing means for directing the input repetitive light pulse signal into the microcavity for resonating therein, and for directing a reference repetitive light pulse signal of ultra-short repeating light pulses into the microcavity for resonating therein, and a means for progressively altering the phases relative to each other at which the light pulses of the respective input and reference light pulse signals enter the microcavity to produce a pulsed photocurrent from which the pulse width of the light pulses of the input light pulse signal is determined.
A method for determining the pulse width of light pulses of an input repetitive light pulse signal of repeating ultra-short light pulses, the method comprising providing a two-photon absorption detector in the form of a microcavity, whereby the microcavity comprises an active region and spaced apart first and second reflecting means between which the active region is located, and within which light resonates to produce a photocurrent as a result of the two-photon absorption effect, selecting the active region and the first and second reflecting means so that the resonating lifetime of light in the microcavity is less than the pulse width of the light pulses, the pulse width of which is to be determined, directing the input repetitive light pulse signal into the microcavity for resonating therein, directing a reference repetitive light pulse signal of ultra-short repeating light pulses into the microcavity for resonating therein, and progressively altering the phases relative to each other at which the light pulses of the respective input and reference light pulse signals enter the microcavity to produce a pulsed photocurrent from which the pulse width of the light pulses of the input light pulse signal is determined.
A photodetector device for detecting light of any one of a plurality of wavelengths within a predetermined range of wavelengths of an input light pulse of ultra-short duration, the photodetector device comprising a two-photon absorption detector comprising an active region within which incident light resonates to produce a detectable photocurrent as a result of the two-photon absorption effect, the two-photon absorption detector defining an incident surface for receiving incident light therethrough to the active region, and a light directing means for directing the input light pulse into the active region through the incident surface, one of the light directing means and the two-photon absorption detector being moveable relative to the other for varying the angle of incidence at which the input light pulse is incident on the incident surface for determining the wavelength of the input light pulse to which the photodetector device is responsive, so that when the light of the input light pulse contains light of the determined wavelength, the light of the input light pulse resonates in the active region to produce the detectable photocurrent.
A method for detecting light of any one of a plurality of wavelengths within a predetermined range of wavelengths of an input light pulse of ultra-short duration, the method comprising providing a two-photon absorption photodetector having an active region within which light resonates to produce a detectable photocurrent as a result of the two-photon absorption effect, the two-photon absorption detector defining an incident surface for receiving incident light therethrough to the active region, and providing a light directing means for directing the input light pulse into the active region through the incident surface, and moving one of the light directing means and the two-photon absorption detector relative to the other for varying the angle of incidence at which the input light pulse is incident on the incident surface for determining the wavelength of the input light pulse to which the photodetector device is responsive, so that when the input light pulse contains light of the determined wavelength, the input light pulse resonates in the active region to produce the detectable photocurrent.
Dependencies are inferred from the claim text.