Two-dimensional microlens arrays in silica-on-silicon planar lightwave circuit technology

Abstract

Two-dimensional (2-D) microlens arrays have been fabricated with silica-on-silicon planar lightwave circuit (PLC) technology. Several experimental techniques and computer simulation methods are applied to characterize properties of single and double microlens arrays, with one and two refracting surfaces, respectively. Systematic comparison of the measured and simulated beam propagation profiles enables optimization of the lens and module design resulting in higher input-output coupling efficiency. The insertion losses of the lens-slab-lens optical modules with 90-mm-long slab waveguides are measured to be 2.1 and 3.5 dB for the double and single lens modules, respectively. Comprehensive analysis reveals the major loss contributions. Excess losses of the modules caused by variations of the lens curvatures, material refractive indexes, light wavelength, etc., can be controlled within the acceptable limits. Further possibilities for the module loss reduction are discussed. Fairly weak wavelength dependence as well as overall stability of the module properties indicate that the microlens arrays are suitable for dense wavelength division multiplexing (DWDM) photonic networks.

Angle Selective Enhancement of Beam Deflection in High-Speed Electrooptic Switches

“…A scanning electron microscope (SEM) image of the microlens in Fig. 3(b) shows the shape of the microlens front side, which is formed by reactive ion etching and enables lateral collimation of light beams with widths of 200-500 m [9]. The light is confined vertically in the slab WG.…”

“…The microlens design, fabrication, and properties were reported in detail in [9] and [10]. The lenses are formed on silica or silicon substrates by deposition and etching of three silica layers: lower cladding, core, and upper cladding.…”

Planar waveguide microlenses for nonblocking photonic switches and optical interconnects

“…Further details of the simulation techniques can be found in Ref. [10]. Beam propagation profiles for four lenses with design parameters from Tables 1 and 2 are shown in Fig.…”

“…More details on the lens designs can be found in reference [10]. The two lens types are presented in Fig.…”

“…In the 2D nonblocking crossconnect architecture the light is confined in a slab waveguide vertically and propagates without confinement in the lateral direction [7]. Thus, 2D planar microlens arrays are required in order to collimate and focus the light beams laterally [8][9][10]. Design rules of many optical interconnect or photonic switching systems require that the light beams be collimated at distances of more than 100 mm.…”