Directly laser-written integrated photonics devices including diffractive optical elements

Advances in femtosecond laser processing of optical material for device applications

“…Since then, the fabrication and light‐guiding efficiency has been significantly improved to increase the possibility of a practical use of the technique. In this period, more complicated structures including waveguide arrays, couplers, stacked diffractive optics, and integrated optical devices were demonstrated …”

“…Integrated optics are composed of at least two different functional structures such as a combination of waveguide and diffractive structures, and a built‐in coupler with a diffractive lens and waveguide array. Choi, et al demonstrated a 1 × 3 built‐in coupler which combined three‐layer stacked FZPs and waveguides, as shown in Figure . Each layer of stacked FZPs are laterally placed with 60 µm which is the same distance of each waveguides, so that the FZPs work as focusing lenses and splitter at the same time.…”

“…(A) Optical microscopic image of the fs written waveguide array and stacked FZPs (B, C) the propagation profiles of the beam coupling through three adjacent waveguides. [Reprinted/Adapted] with permission from reference [22] © Elsevier Ltd [Color figure can be viewed at wileyonlinelibrary.com]…”

“…In this period, more complicated structures including waveguide arrays, couplers, stacked diffractive optics, and integrated optical devices were demonstrated. [22][23][24] In recent years, this technique has matured to achieve sufficient reliability for commercialization of directly laser written components which are not available with current fiber-optic technology. A few start-up companies are established based on unique business areas such as fiber 3D interconnect and 3D fan-out multiplexers toward the future markets in the fields including optical networking, quantum communication, and optical sensing.…”

“…Choi, et al demonstrated a 1 × 3 built-in coupler which combined three-layer stacked FZPs and waveguides, as shown in Figure 1. 22 Each layer of stacked FZPs are laterally placed with 60 µm which is the same distance of each waveguides, so that the FZPs work as focusing lenses and splitter at the same time. The FZPs were written one of the subsurfaces in front of the waveguides, therefore it has resistance to the external vibration.…”