OPTICAL PULSE GENERATING APPARATUS, TERAHERTZ SPECTROSCOPY APPARATUS, AND TOMOGRAPHY APPARATUS

• US 20130146769A1
• Filed: 07/26/2011
• Published: 06/13/2013
• Est. Priority Date: 08/27/2010
• Status: Abandoned Application

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ouchi, Toshihiko
• Application Number:
  US13/818,607
• Publication Number:
  US 20130146769A1
• Time in Patent Office: Days
• US Class Current: 250/338.1
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/42 Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry beam switching arrangements G01J3/08
• CPC Class Codes: G01J 3/4338 Frequency modulated spectrometry
• CPC Class Codes: G01N 2021/1787 Tomographic, i.e. computerised reconstruction from projective measurements
• CPC Class Codes: G01N 21/17 Systems in which incident light is modified in accordance with the properties of the material investigated where the material investigated is optically excited causing a change in wavelength of the incident light G01N21/63
• CPC Class Codes: G01N 21/3581 using far infrared light; using Terahertz radiation
• CPC Class Codes: G01N 2201/067 Electro-optic, magneto-optic, acousto-optic elements
• CPC Class Codes: G02F 1/212 Mach-Zehnder type
• CPC Class Codes: G02F 1/2255 controlled by a high-frequency electromagnetic component in an electric waveguide structure
• CPC Class Codes: G02F 2203/54 Optical pulse train (comb) synthesizer

Abstract

An optical pulse generating apparatus that supplies pump light and probe light includes a light source and a modulation unit configured to modulate light emitted from the light source, thereby dividing the light into the pump light and the probe light. The modulation unit is configured such that a frequency for modulating the light is variable. The modulation unit changes a difference between a moment of the pump light incident on an object and a moment of the probe light incident on the object by changing the frequency.

Claims

1. An optical pulse generating apparatus that supplies pump light and probe light, the optical pulse generating apparatus comprising:

a light source; and

a modulation unit configured to modulate light emitted from the light source, thereby dividing the light into the pump light and the probe light,

wherein the modulation unit is configured such that a frequency for modulating the light is variable, and

wherein the modulation unit changes a difference between a moment of the pump light incident on an object and a moment of the probe light incident on the object by changing the frequency.

2. The optical pulse generating apparatus according to claim 1,

wherein the modulation unit includes an electro-optical modulator or acousto-optic modulator, and

wherein the modulation unit divides the light into the pump light and the probe light by performing binary modulation on the electro-optical modulator or the acousto-optic modulator.

3. The optical pulse generating apparatus according to claim 2,

wherein the modulation unit includes a power supply,

wherein the electro-optical modulator is a Mach-Zehnder modulator, and

wherein the modulation unit divides the light into the pump light and the probe light by performing on-off keying on the electro-optical modulator using the power supply.

4. The optical pulse generating apparatus according to claim 2,

wherein the modulation unit includes a digital signal source that turns on and off a radio frequency signal to be applied to the acousto-optic modulator, and

wherein the modulation unit divides the light into the pump light and the probe light by turning on and off the radio frequency signal to be applied to the acousto-optic modulator using the digital signal source.

9. The optical pulse generating apparatus according to claim 1, further comprising:

a first optical amplifier configured to amplify the pump light;

a first dispersion compensation unit configured to condense the pump light that has been amplified by the first optical amplifier;

a second optical amplifier configured to amplify the probe light; and

a second dispersion compensation unit configured to condense the probe light that has been amplified by the second optical amplifier.

10. The optical pulse generating apparatus according to claim 1,

wherein the modulation unit changes a difference between a moment of the pump light incident on a terahertz wave generating element and a moment of the probe light incident on a terahertz wave detecting element by changing the frequency.

11. The optical pulse generating apparatus according to claim 1,

wherein the modulation unit changes a difference between a moment of the pump light incident on an object and a moment of the probe light incident on the object to be measured by changing the frequency.

12. A terahertz spectroscopy apparatus comprising:

the optical pulse generating apparatus according to claim 1;

a terahertz wave generating element configured to be irradiated by the pump light emitted by the optical pulse generating apparatus; and

a terahertz wave detecting element configured to be irradiated by the probe light emitted by the optical pulse generating apparatus.

13. A tomography apparatus comprising:

the optical pulse generating apparatus according to claim 1;

a terahertz wave generating element configured to be irradiated by the pump light emitted by the optical pulse generating apparatus; and

a terahertz wave detecting element configured to be irradiated by the probe light emitted by the optical pulse generating apparatus.

5. An optical pulse generating apparatus that supplies pump light and probe light, the optical pulse generating apparatus comprising:

a light source;

a modulation unit configured to modulate an oscillation state of the light source; and

a dividing unit configured to divide light emitted from the light source into the pump light and the probe light,

wherein the modulation unit is configured such that a frequency for modulating the oscillation state is variable, and

wherein the modulation unit changes a difference between a moment of the pump light incident on an object and a moment of the probe light incident on the object by changing the frequency.

6. The optical pulse generating apparatus according to claim 5,

wherein the light source is a polarization modulation laser,

wherein the modulation unit changes a polarization direction of the polarization modulation laser, and

wherein the dividing unit is a polarizing beam splitter.

14. A terahertz spectroscopy apparatus comprising:

the optical pulse generating apparatus according to claim 5;

a terahertz wave generating element configured to be irradiated by the pump light emitted by the optical pulse generating apparatus; and

a terahertz wave detecting element configured to be irradiated by the probe light emitted by the optical pulse generating apparatus.

15. A tomography apparatus comprising:

the optical pulse generating apparatus according to claim 5;

a terahertz wave generating element configured to be irradiated by the pump light emitted by the optical pulse generating apparatus; and

a terahertz wave detecting element configured to be irradiated by the probe light emitted by the optical pulse generating apparatus.

7. An optical pulse generating apparatus that supplies pump light and probe light, the optical pulse generating apparatus comprising:

a light source; and

a modulation unit configured to modulate an oscillation state of the light source,

wherein the light source includes a dividing unit that divides light such that the light source outputs the pump light and the probe light,

wherein the modulation unit is configured such that a frequency for modulating the oscillation state is variable, and

wherein the modulation unit changes a difference between a moment of the pump light incident on an object and a moment of the probe light incident on the object by changing the frequency.

8. The optical pulse generating apparatus according to claim 7,

wherein the light source is a ring laser,

wherein the modulation unit changes a circulation direction of the ring laser, and

wherein the dividing unit is a coupler.

16. A terahertz spectroscopy apparatus comprising:

the optical pulse generating apparatus according to claim 7;

a terahertz wave generating element configured to be irradiated by the pump light emitted by the optical pulse generating apparatus; and

a terahertz wave detecting element configured to be irradiated by the probe light emitted by the optical pulse generating apparatus.

17. A tomography apparatus comprising:

the optical pulse generating apparatus according to claim 7;

a terahertz wave generating element configured to be irradiated by the pump light emitted by the optical pulse generating apparatus; and

a terahertz wave detecting element configured to be irradiated by the probe light emitted by the optical pulse generating apparatus.