US 12,332,408 B2
Anti-reflective optical structures for optical systems
Mohamed Mahmoud, Sunnyvale, CA (US); Huiyang Deng, San Jose, CA (US); Satyarth Suri, San Jose, CA (US); Jason S. Pelc, Sunnyvale, CA (US); and Peter L. Chang, San Jose, CA (US)
Assigned to Apple Inc., Cupertino, CA (US)
Filed by Apple Inc., Cupertino, CA (US)
Filed on Mar. 9, 2023, as Appl. No. 18/119,591.
Claims priority of provisional application 63/400,254, filed on Aug. 23, 2022.
Prior Publication US 2024/0069248 A1, Feb. 29, 2024
Int. Cl. G02B 1/118 (2015.01); G02B 1/02 (2006.01); G02B 6/12 (2006.01); G02B 6/122 (2006.01)
CPC G02B 1/118 (2013.01) [G02B 1/02 (2013.01); G02B 6/122 (2013.01); G02B 2006/12038 (2013.01); G02B 2006/12061 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An anti-reflective optical structure comprising:
a light-transmissive element formed from a semiconductor material, the light-transmissive element having a transmission surface defining a first sub-wavelength grating;
a first layer formed from a first material and disposed onto at least a portion of the first sub-wavelength grating, the first layer together with the first sub-wavelength grating defining a first refractive index gradient and the first material having a refractive index less than a refractive index of the semiconductor material; and
a second layer formed from a second material, disposed over the first layer, and defining a second sub-wavelength grating, the second sub-wavelength grating defining a second refractive index gradient and the second material having a refractive index that is less than the refractive index of the semiconductor material and greater than the refractive index of the first material.