Broadband, millimeter-wave anti-reflective structures on sapphire ablated with femto-second laser

Ryota Takaku; S. Hanany; H. Imada; H. Ishino; N. Katayama; K. Komatsu; K. Konishi; M. Kuwata-Gonokami; T. Matsumura; K. Mitsuda; H. Sakurai; Y. Sakurai; Q. Wen; N. Y. Yamasaki; K. Young; J. Yumoto

Broadband, millimeter-wave anti-reflective structures on sapphire ablated with femto-second laser

Ryota Takaku, S. Hanany, H. Imada, H. Ishino, N. Katayama, K. Komatsu, K. Konishi, M. Kuwata-Gonokami, T. Matsumura, K. Mitsuda, H. Sakurai, Y. Sakurai, Q. Wen, N. Y. Yamasaki, K. Young, J. Yumoto

Research output: Contribution to journal › Article › peer-review

Abstract

We designed, fabricated, and measured anti-reflection coating (ARC) on sapphire that has 116% fractional bandwidth and transmission of at least 97% in the millimeter wave band. The ARC was based on patterning pyramid-like subwavelength structures (SWS) using ablation with a 15 W femto-second laser operating at 1030 nm. One side of each of two discs was fabricated with SWS that had a pitch of 0.54 mm and height of 2 mm. The average ablation volume removal rate was 1.6 mm³/min. Measurements of the two-disc sandwich show transmission higher than 97% between 43 and 161 GHz. We characterize instrumental polarization (IP) arising from differential transmission due to asymmetric SWS. We find that with proper alignment of the two disc sandwich RMS IP across the band is predicted to be 0.07% at normal incidence, and less than 0.6% at incidence angles up to 20 degrees. These results indicate that laser ablation of SWS on sapphire and on other hard materials such as alumina is an effective way to fabricate broad-band ARC.

Original language	English
Journal	Unknown Journal
Publication status	Published - Jul 30 2020

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Broadband, millimeter-wave anti-reflective structures on sapphire ablated with femto-second laser. / Takaku, Ryota; Hanany, S.; Imada, H.; Ishino, H.; Katayama, N.; Komatsu, K.; Konishi, K.; Kuwata-Gonokami, M.; Matsumura, T.; Mitsuda, K.; Sakurai, H.; Sakurai, Y.; Wen, Q.; Yamasaki, N. Y.; Young, K.; Yumoto, J.

In: Unknown Journal, 30.07.2020.

Research output: Contribution to journal › Article › peer-review

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title = "Broadband, millimeter-wave anti-reflective structures on sapphire ablated with femto-second laser",

abstract = "We designed, fabricated, and measured anti-reflection coating (ARC) on sapphire that has 116% fractional bandwidth and transmission of at least 97% in the millimeter wave band. The ARC was based on patterning pyramid-like subwavelength structures (SWS) using ablation with a 15 W femto-second laser operating at 1030 nm. One side of each of two discs was fabricated with SWS that had a pitch of 0.54 mm and height of 2 mm. The average ablation volume removal rate was 1.6 mm3/min. Measurements of the two-disc sandwich show transmission higher than 97% between 43 and 161 GHz. We characterize instrumental polarization (IP) arising from differential transmission due to asymmetric SWS. We find that with proper alignment of the two disc sandwich RMS IP across the band is predicted to be 0.07% at normal incidence, and less than 0.6% at incidence angles up to 20 degrees. These results indicate that laser ablation of SWS on sapphire and on other hard materials such as alumina is an effective way to fabricate broad-band ARC.",

author = "Ryota Takaku and S. Hanany and H. Imada and H. Ishino and N. Katayama and K. Komatsu and K. Konishi and M. Kuwata-Gonokami and T. Matsumura and K. Mitsuda and H. Sakurai and Y. Sakurai and Q. Wen and Yamasaki, {N. Y.} and K. Young and J. Yumoto",

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TY - JOUR

T1 - Broadband, millimeter-wave anti-reflective structures on sapphire ablated with femto-second laser

AU - Takaku, Ryota

AU - Hanany, S.

AU - Imada, H.

AU - Ishino, H.

AU - Katayama, N.

AU - Komatsu, K.

AU - Konishi, K.

AU - Kuwata-Gonokami, M.

AU - Matsumura, T.

AU - Mitsuda, K.

AU - Sakurai, H.

AU - Sakurai, Y.

AU - Wen, Q.

AU - Yamasaki, N. Y.

AU - Young, K.

AU - Yumoto, J.

PY - 2020/7/30

Y1 - 2020/7/30

N2 - We designed, fabricated, and measured anti-reflection coating (ARC) on sapphire that has 116% fractional bandwidth and transmission of at least 97% in the millimeter wave band. The ARC was based on patterning pyramid-like subwavelength structures (SWS) using ablation with a 15 W femto-second laser operating at 1030 nm. One side of each of two discs was fabricated with SWS that had a pitch of 0.54 mm and height of 2 mm. The average ablation volume removal rate was 1.6 mm3/min. Measurements of the two-disc sandwich show transmission higher than 97% between 43 and 161 GHz. We characterize instrumental polarization (IP) arising from differential transmission due to asymmetric SWS. We find that with proper alignment of the two disc sandwich RMS IP across the band is predicted to be 0.07% at normal incidence, and less than 0.6% at incidence angles up to 20 degrees. These results indicate that laser ablation of SWS on sapphire and on other hard materials such as alumina is an effective way to fabricate broad-band ARC.

AB - We designed, fabricated, and measured anti-reflection coating (ARC) on sapphire that has 116% fractional bandwidth and transmission of at least 97% in the millimeter wave band. The ARC was based on patterning pyramid-like subwavelength structures (SWS) using ablation with a 15 W femto-second laser operating at 1030 nm. One side of each of two discs was fabricated with SWS that had a pitch of 0.54 mm and height of 2 mm. The average ablation volume removal rate was 1.6 mm3/min. Measurements of the two-disc sandwich show transmission higher than 97% between 43 and 161 GHz. We characterize instrumental polarization (IP) arising from differential transmission due to asymmetric SWS. We find that with proper alignment of the two disc sandwich RMS IP across the band is predicted to be 0.07% at normal incidence, and less than 0.6% at incidence angles up to 20 degrees. These results indicate that laser ablation of SWS on sapphire and on other hard materials such as alumina is an effective way to fabricate broad-band ARC.

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