Solid state etalons with low thermally-induced optical path length change employing crystalline materials having significantly negative temperature coefficients of optical path length

• US 20040080832A1
• Filed: 06/26/2003
• Published: 04/29/2004
• Est. Priority Date: 06/28/2002
• Status: Abandoned Application

• Current Assignee: GSI Lumonics Corporation (Novanta Inc.)
• Original Assignee: GSI Lumonics Corporation (Novanta Inc.)
• Inventors: Singh, Mandeep
• Application Number:
  US10/606,685
• Publication Number:
  US 20040080832A1
• Time in Patent Office: Days
• US Class Current: 359/578
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G02B 5/284 of etalon type comprising a resonant cavity other than a thin solid film, e.g. gas, air, solid plates etalons for fibre optic multiplexing G02B6/29358; etalons for spectral measurement G01J3/26
• CPC Class Codes: G02B 6/29358 Multiple beam interferometer external to a light guide, e.g. Fabry-Pérot, etalon, VIPA plate, OTDL plate, continuous interferometer, parallel plate resonator G02B6/29347, G02B6/29349, G02B6/2935, G02B6/29361 take precedence; resonator evanescently coupled to light guide G02B6/29335
• CPC Class Codes: G02B 6/29398 Temperature insensitivity

Abstract

An etalon is disclosed comprising a first rutile or strontium titanate material having a first coefficient of thermal optical path length change β₁ that has a negative value, coupled with a second material having a coefficient of thermal optical path length change β₂ that is positive, and an optical path extending through the first material and the second material, such that the effective temperature coefficient of the optical path length is close to zero. Further, the total optical path length in the cavity gives a desired free spectral range of the etalon. Etalons composed of a single crystalline material are also disclosed. Such materials may include crystalline quartz.

Claims

1. An etalon comprising:

a first rutile material having a first coefficient of thermal optical path length change β

₁;

a second material having a second coefficient of thermal optical path length change β

₂;

an optical path extending through said first material and said second material, wherein one of β

₁ and β

₂ is negative.

2. The etalon as claimed in claim 1, wherein said second material includes an optical glass.

3. The etalon as claimed in claim 1, wherein said second material includes Bk7.

4. The etalon as claimed in claim 1, wherein said second material includes a crystal.

5. The etalon as claimed in claim 1, wherein said second material includes a quartz.

6. The etalon as claimed in claim 1, wherein said etalon further includes an anti-reflective coating between said first rutile material and said second material.

7. An etalon comprising:

a first material having a first thickness d₁, a first index of refraction n₁, and a first coefficient of thermal optical path length change β

₁, wherein β

₁<

−

1.0;

a second material having a second thickness d₂, a second index of refraction n₂, and a second coefficient of thermal optical path length change β

₂, wherein the ratio d₁/d₂ equals-(n₂β

₂ )/(n₁β

₁).

8. The etalon as claimed in claim 7, wherein −

7 >

β

₁>

−

25.

9. The etalon as claimed in claim 7, wherein said etalon includes BK7.

10. The etalon as claimed in claim 7, wherein said etalon includes quartz.

11. The etalon as claimed in claim 7, wherein said etalon includes silicon.

12. An etalon including strontium titanate.

13. An etalon including a rutile material and a coefficient of optical path length that is approximately zero.

14. An etalon including a strontium titanate material having a negative β

, a positive β

material, and a coefficient of optical path length that is approximately zero.

15. An etalon comprising:

a rutile material having a first thickness d₁, a first index of refraction n₁, and a first coefficient of thermal optical path length change β

₁;

a glass material having a second thickness d₂, a second index of refraction n₂, and a second coefficient of thermal optical path length change β

₂ , wherein the ratio d₁/d₂ equals-(n₂β

₂ )/(n₁β

₁).