Infrared (IR) photon-sensitive spectromicroscopy in a cryogenic environment

Patent metadata

Field	Value
Publication number	US-9366574-B2
Application number	US-201514642631-A
Country	US
Kind code	B2
Filing date	Mar 9, 2015
Priority date	Mar 7, 2014
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

A system designed to suppress thermal radiation background and to allow IR single-photon sensitive spectromicroscopy of small samples by using both absorption, reflection, and emission/luminescence measurements. The system in one embodiment includes: a light source; a plurality of cold mirrors configured to direct light along a beam path; a cold or warm sample holder in the beam path; windows of sample holder (or whole sample holder) are transparent in a spectral region of interest, so they do not emit thermal radiation in the same spectral region of interest; a cold monochromator or other cold spectral device configured to direct a selected fraction of light onto a cold detector; a system of cold apertures and shields positioned along the beam path to prevent unwanted thermal radiation from arriving at the cold monochromator and/or the detector; a plurality of optical, IR and microwave filters positioned along the beam path and configured to adjust a spectral composition of light incident upon the sample under investigation and/or on the detector; a refrigerator configured to maintain the detector at a temperature below 1.0K; and an enclosure configured to: thermally insulate the light source, the plurality of mirrors, the sample holder, the cold monochromator and the refrigerator.

First claim

What is claimed is:

1. A photon-sensitive infrared (IR) spectromicroscopy system, comprising:
a light source;
a plurality of cold mirrors configured to direct light emitted from the light source along a beam path;
a sample holder positioned in the beam path and having portions transparent in at least a spectral range of interest, so light in the spectral range of interest is not absorbed and not emitted by the portions;
a spectral device configured to direct a selected wavelength of light, polarization of light, and/or plurality thereof onto a detector;
a plurality of cold apertures and a plurality of shields positioned along the beam path, the cold apertures and shields being configured to prevent thermal emission originating from the sample holder from reaching the detector;
a sub-K refrigerator configured to maintain a detector temperature below an upper operational temperature threshold less than about 1.0 K; and
an enclosure configured to thermally insulate the light source, the plurality of mirrors, the spectral device and the sub-K refrigerator; and
wherein the sample holder is characterized by a path length less than a radiation equilibration length of a medium through which light from the light source travels.

2. The system as recited in claim 1 , wherein the system is characterized by a lower detection limit of approximately a single photon.

3. The system as recited in claim 1 , wherein the system is characterized by a lower detection limit of a single photon, wherein the single photon is characterized by a wavelength greater than about 1 micron and less than about 350 microns.

4. The system as recited in claim 1 , wherein the enclosure is further configured to: maintain the detector temperature in a range from about 0.1 K to about 1.0 K; and
optically insulate, the light source, the plurality of mirrors, the sample holder, and the spectral device.

5. The system as recited in claim 1 , wherein the sample holder comprises two windows characterized by a gap therebetween.

6. The system as recited in claim 1 , wherein the detector comprises a Cooper Pair Box-type detector.

7. The system as recited in claim 1 , wherein the light source comprises a pulsed monochromatic quantum cascade laser (QCL).

8. The system as recited in claim 1 , further comprising at least one filter in the enclosure, the filter being configured to block thermal microwave radiation characterized by a wavelength greater than a first wavelength threshold; and
wherein the at least one filter comprises a metal foil mesh.

9. The system as recited in claim 1 , wherein the detector is a transition edge sensor, and further comprising a superconducting solenoid installed next to the detector, to cause a superconducting transition temperature of the transition edge sensor to be at a desired temperature range; and
wherein the superconducting solenoid has a core comprising iron.

10. The system as recited in claim 1 , wherein the detector comprises a titanium transition-edge sensor (TES);
wherein the detector is disposed as a film on a silicon substrate; and
wherein the film of the TIS is characterized by a volume of approximately 0.1 μm 3 .

11. The system as recited in claim 1 , wherein the detector comprises a bridge, the bridge comprising:
a first superconducting material; and
a second superconducting material, the second superconducting material having a superconducting transition temperature (Tc) higher than a Tc of the first superconducting material;
wherein the first superconducting material is in electrical contact with the second superconducting material; and
wherein the bridge is characterized by a length less than a mid-IR radiation wavelength.

12. The system as recited in claim 11 , wherein the first superconducting material is selected from a group consisting of titanium, titanium nitrite, and a molybdenum-gold alloy; and
wherein the second superconducting material is selected from a group consisting of niobium, lead, tin, aluminum, and a niobium-titanium alloy.

13. The system as recited in claim 11 , wherein the bridge is effectively coupled to radiation generated by a micro-antenna comprising one or more of gold and a niobium film.

14. The system as recited in claim 11 , wherein the bridge is a microwave resonator.

15. The system as recited in claim 11 , wherein the second superconducting material is arranged into one or more photon absorbing fins.

16. The system as recited in claim 1 , wherein the sample holder is positioned outside the enclosure and configured to maintain nonequilibirum thermodynamic conditions at a temperature of approximately 300K for a sample in aqueous solution placed in the sample holder; and
wherein a path length of the sample holder is less than a radiation equilibration length of water in a spectral region of interest.

17. A photon-sensitive infrared (IR) spectromicroscopy system, comprising:
a light source;
a plurality of cold mirrors configured to direct light emitted from the light source along a beam path;
a sample holder positioned in the beam path and having portions transparent in at least the spectral range of interest, so light in the spectral range of interest is not absorbed and not emitted by the portions;
a spectral device configured to direct a selected wavelength of light, polarization of light, and/or plurality thereof onto a detector;
a plurality of cold apertures and a plurality of shields positioned along the beam path, the cold apertures and shields being configured to prevent thermal emission originating from the sample holder from reaching the detector;
a sub-K refrigerator configured to maintain a detector temperature below an upper operational temperature threshold less than about 1.0 K; and
an enclosure configured to thermally insulate the light source, the plurality of mirrors, the sample holder, the spectral device and the sub-K refrigerator;
wherein the sample holder comprises two windows characterized by a gap therebetween;
wherein the gap is characterized by a thickness t, and
wherein t is approximately equal to a smallest dimension of a cell that would allow the cell to enter or pass through the gap without being damaged.

18. The system as recited in claim 5 , wherein the windows are each transparent to light having a wavelength in a range between about 1.5 μm to about 0.1 mm.

19. A photon-sensitive infrared (IR) spectromicroscopy system, comprising:
a light source;
a plurality of cold mirrors configured to direct light emitted from the light source along a beam path;
a sample holder positioned in the beam path and having portions transparent in at least the spectral range of interest, so light in the spectral range of interest is not absorbed and not emitted by the portions;
a spectral device configured to direct a selected wavelength of light, polarization of light, and/or plurality thereof onto a detector;
a plurality of cold apertures and a plurality of shields positioned along the beam path, the cold apertures and shields being configured to prevent thermal emission originating from the sample holder from reaching the detector;
a sub-K refrigerator configured to maintain a detector temperature below an upper operational temperature threshold less than about 1.0 K; and
an enclosure configured to thermally insulate the light source, the plurality of mirrors, the sample holder, the spectral device and the sub-K refrigerator;
wherein the detector is a transition edge sensor, and further comprising a superconducting solenoid installed next to the det

Assignees

• L Livermore Nat Security Llc

Inventors

• Pereverzev Sergey

Classifications

• G01J3/18

  using diffraction elements, e.g. grating (gratings per se G02B) · CPC title

• G01J5/061 Primary

  by controlling the temperature of the apparatus or parts thereof, e.g. using cooling means or thermostats · CPC title

• G01J3/021

  using plane or convex mirrors, parallel phase plates, or particular reflectors · CPC title