6C004 Category 6C

Optical materials as follows (see List of Items Controlled).

Category 6: Sensors and Lasers

Reasons for control

• NS: National security
• AT: Anti-terrorism

Country chart

List-based license exceptions

Items

1. Items: a. Zinc selenide (ZnSe) and zinc sulfide (ZnS) “substrate blanks”, produced by the chemical vapor deposition process and having any of the following:
2. a.1. A volume greater than 100 cm 3; or
3. a.2. A diameter greater than 80 mm and a thickness of 20 mm or more;
4. b. Electro-optic materials and non-linear materials, as follows:
5. b.1. Potassium titanyl arsenate (KTA) (CAS 59400-80-5);
6. b.2. Silver gallium selenide (AgGaSe2, also known as AGSE) (CAS 12002-67-4);
7. b.3. Thallium arsenic selenide (Tl3AsSe3, also known as TAS) (CAS 16142-89-5);
8. b.4. Zinc germanium phosphide (ZnGeP2, also known as ZGP, zinc germanium biphosphide or zinc germanium diphosphide); or
9. b.5. Gallium selenide (GaSe) (CAS 12024-11-2);
10. c. Non-linear optical materials, other than those specified by 6C004.b, having any of the following:
11. c.1. Having all of the following:
12. c.1.a. Dynamic (also known as nonstationary) third order nonlinear susceptibility (χ(3), chi 3) of 10−6 m 2/V 2 or more; and
13. c.1.b. Response time of less than 1 ms; or
14. c.2. Second order nonlinear susceptibility (χ(2), chi 2) of 3.3 × 10−11 m/V or more;
15. d. “Substrate blanks” of silicon carbide or beryllium beryllium (Be/Be) deposited materials, exceeding 300 mm in diameter or major axis length;
16. e. Glass, including fused silica, phosphate glass, fluorophosphate glass, zirconium fluoride (ZrF4) (CAS 7783-64-4) and hafnium fluoride (HfF4) (CAS 13709-52-9) and having all of the following:
17. e.1. A hydroxyl ion (OH-) concentration of less than 5 ppm;
18. e.2. Integrated metallic purity levels of less than 1 ppm; and
19. e.3. High homogeneity (index of refraction variance) less than 5 × 10−6;
20. f. Synthetically produced diamond material with an absorption of less than 10−5 cm−1 for wavelengths exceeding 200 nm but not exceeding 14,000 nm.

Related controls

See also 6C994

Source: eCFR, version 2026-08-01, retrieved 2026-08-20T04:04:59+00:00.