Design methodology of focusing elements for multilevel planar optical systems in optical interconnects

Abstract

We present a simple technique to determine the design parameters of an optical interconnect system that uses integral planar lenses. The technique is based on the ABCD transformation matrix method. This analysis technique is significantly simpler and more efficient than the previously published methods for finding the design parameters and predicting the coupling efficiency of the system. The proposed method is applied to compute the coupling efficiency of singleand two-level optical systems.

Planar microlens with front-face angle: design, fabrication, and characterization

“…It is important to note that using the reformulated 3 × 3 ABCDGH transfer matrix method, individual loss contribution from input/output optical fiber tilt and offset, both in the vertical and horizontal directions, as well as microlens front-face slopes can be evaluated, which was not possible with the previous approach in Ref. 13.…”

“…10 Other applications that can benefit from the development of such planar microlens pairs include free-space optical interconnects on chip. 11 The analysis of a planar microlens pair that allows lowloss free-space transmission of light between two opposing waveguides/fibers has been reported 12,13 for potential applications in optical cross-connect switches and optical interconnects. In Ref.…”

“…In Ref. 13, a 2 × 2 ABCD matrix method for designing and computing the coupling efficiency of optical systems comprising planar microlens pair was developed. This analysis was based on the assumption that the components in the optical system are in alignment with the axis of light propagation that has a perfectly vertical microlens front face and properly aligned input/output optical fibers at the input/output butt-coupling ends.…”

Fabrication and optical characterisation of planar silica lens pair

“…Their low index contrast enables mode matching and easy alignment to optical fibres, which has been crucial to their success in telecommunications applications. A planar lens pair which allows the low-loss transmission of light between two opposing waveguides has been theoretically analysed and simulated [1,2] for intended application in optical crossconnect switches and optical interconnects. The lens pair uses a parabolic graded index silica slab to guide the optical beam in the vertical direction and a convex curvature front face, defined by a deep oxide etch, to guide the light in the horizontal direction.…”

“…The vertical spot size at the mid-point of the free-space propagation distance, v cx , was chosen for the lens pair design. By means of the ABCD matrix method described in [2] and designed parameter values shown in Table 1a, the following parameters are computed and listed in Table 1b: (i) horizontal spot size at the lens/air interface, v iy ; (ii) horizontal spot size at the mid-point of the free-space propagation distance, v cy ; (iii) maximum vertical spot size in the lens section, v mx ; (iv) radius of the curvature defining the convex shape, R, (v) lens length, L; (vi) focusing parameter, a = 2D √ /r; (vii) minimum refractive index of the graded index profile, n cl ; and (viii) half-width of the parabolic graded index profile, r. [4]. Oxygen and silane flow rates were fixed at 100 and 15 sccm, respectively, while the CF 4 flow rate was varied from 26 -30 sccm at RF power of 300 W and pressure of 10 mTorr to change the refractive index from 1.4 to 1.393.…”