Solution Processing and Resist‐Free Nanoimprint Fabrication of Thin Film Chalcogenide Glass Devices: Inorganic–Organic Hybrid Photonic Integration

Abstract

Organic polymer materials are widely credited with extreme versatility for thin film device processing. However, they generally lack the high refractive indices of inorganic semiconductors essential for tight optical confinement in planar integrated photonic circuits. Inorganic–organic hybrid photonic systems overcome these limits by combining both types of materials, although such hybrid integration remains challenging given the vastly different properties of the two types of materials. In this paper, a new approach is used to realize inorganic–organic hybrid photonics using chalcogenide glass (ChG) materials. Known as an amorphous semiconductor, the glass possesses high refractive indices, and can be prepared in a thin film form through solution deposition and patterned via direct thermal nanoimprinting, processing methods traditionally exclusive to polymer materials only. Sub‐micrometer waveguides, microring resonators, and diffraction gratings fabricated from solution processed (SP) ChG films can be monolithically integrated with organic polymer substrates to create mechanically flexible, high‐index‐contrast photonic devices. The resonators exhibit a high quality factor (Q‐factor) of 80 000 near 1550 nm wavelength. Free‐standing, flexible ChG gratings whose diffraction properties can be readily tailored by conformal integration on nonplanar surfaces are also demonstrated.

High-quality chalcogenide glass waveguide fabrication by hot melt smoothing and micro-trench filling

“…The experimental results demonstrate that the proposed fabrication process can realize high quality ChG waveguide fabrication with low loss transmission in the telecom band. The measured attenuation is comparable with that of the best ChG waveguides fabricated by dry etching, 23,30) and better than that of the ChG waveguides fabricated by lift-off, 24) nano-imprint, 8) or the method based on the organic ammonia solution of ChG. 27) In this paper, we proposed a simple fabrication method for ChG waveguides. Utilizing the low melting point and high flowability of ChG materials, reverse ridge waveguides can be fabricated by hot melt smoothing and micro-trench filling.…”

“…However, the residual solvent may lead to obvious loss when it is used to fabricate optical waveguides in the near-infrared band, since its N-H bonds have an overtone absorption around 1510 nm. 27) ChGs have some interesting properties including low glass transition temperatures and low melting points, which may provide new directions for waveguide fabrication. By proper temperature control so as to prevent crystallization, the shape of ChG films may be modified by the melting and flowing processes.…”

Integrated photonics for infrared spectroscopic sensing

“…These polycrystalline chalcogenides can be readily deposited via chemical bath deposition [52,53] or thermal evaporation, facilitating monolithic integration of active mid-IR photonic devices on common semiconductor or dielectric substrates [54][55][56]. Our previous work has developed deposition and processing of these chalcogenide materials and fabrication protocols of photonic devices operating at near-IR telecommunication wave bands on silicon as well as unconventional substrates such as polymers [57][58][59][60][61][62][63][64][65][66][67][68]. In this paper, we present mid-IR photonic integration based on chalcogenide materials as well as sensing applications of the chip-scale mid-IR photonic platform.…”

Substrate-blind photonic integration based on high-index glass materials

“…Subsequent device fabrication on ChG films were performed using lift-off 15 or thermal nanoimprint [16][17][18] . Both methods are capable of generating sub-micron single-mode optical waveguides.…”