Fabrication of Achromatic Infrared Wave Plate by Direct Imprinting Process on Chalcogenide Glass

Abstract

An achromatic infrared wave plate was fabricated by forming a subwavelength grating on the chalcogenide glass using direct imprint lithography. A low toxic chalcogenide glass (Sb–Ge–Sn–S system) substrate was imprinted with a grating of 1.63-µm depth, a fill factor of 0.7, and 3-µm period using glassy carbon as a mold at 253 °C and 3.8 MPa. Phase retardation of the element reached around 30° at 8.5–10.5 µm wavelengths, and the transmittance exceeded that of a flat substrate over 8 µm wavelength. Fabrication of the mid-infrared wave plate is thereby less expensive than that of conventional crystalline wave plates.

Reflective waveplate with subwavelength grating structure

“…According to the simulation result, the phase retardation is obtainable as around 90°at 405 nm wavelength (Blu-ray wavelength) if the grating pitch, depth, and fill factor were 230 nm, 110 nm, and 0.6 on a Si substrate. Therefore, the waveplate fabrication becomes easier and less costly than fabrication of a transmissive waveplate with subwavelength structure using imprinting process onto polymer or glass plate, 5,6,15,19) reducing the number of elements in the optical pickup units.…”

“…[6][7][8][9] Recently, waveplates with subwavelength structures are in progress through the development of semiconductor manufacturing technology. [10][11][12][13][14][15] A grating with a high aspect ratio and the pitch narrower than wavelength is, however, necessary to obtain a desired phase retardation and lower diffractive loss in the conventional transmissive waveplate.…”

Broadband achromatic phase retarder based on metal-multilayer dielectric grating

“…Kang et al [9] proposed a combination of four sub-wavelength structured gratings used as an achromatic quarter-wave plate, which was applied to MWIR (3-5 µm) & LWIR (8-12 µm) bandwidths based on effective medium theory and optimization algorithms. Yamada et al [10] fabricated an achromatic wave plate by forming a sub-wavelength grating on chalcogenide glass by using direct imprint lithography, with the phase retardation of the element reaching around 30 ∘ at 8.5-10.5 µm wavelength.…”

Size-Dependent Filling Behavior of UV-Curable Di(meth)acrylate Resins into Carbon-Coated Anodic Aluminum Oxide Pores of around 20 nm

“…First, AAO films with a nominal pore diameter have been fabricated over large areas by electrochemical oxidation, and their pore diameter can be tuned in the range of 6–200 nm by selecting suitable oxidation voltage and acidic electrolyte. − In particular, AAO films with a pore diameter of approximately 100 nm are used as UV nanoimprint molds to fabricate optical antireflection polymer films with nanopillars. , Second, thermal chemical vapor deposition (CVD) using acetylene gas as a carbon source produces a ultrathin carbon film on AAO surfaces. For example, an incompletely crystallized carbon film with a thickness of less than 10 nm was deposited all over the outermost and side-wall surfaces of AAO films with a pore diameter of 100 nm and then used as nanoscale carbon tubes. , We anticipated that this carbon film could function as an antisticking layer for UV-cured resins, because glassy carbon molds are used for pattern transfer to fused silica surfaces by thermal nanoimprinting − and the surface free energy of nonpolar carbon films is estimated to be as small as 6.5 mJ m –2 . Third, the size distribution of the pore diameter of AAO films is within approximately 15 nm.…”