1. Date of download: 7/2/2016 Copyright © 2016 SPIE. All rights reserved. Applying Eq. (1) and a thermal analysis for relating junction temperature (Tj) to case temperature (Tc) for different aperture diameters at a case temperature of 25°C versus current density, and comparing with published data in Ref. 24 under those same conditions. The overall shape and trends of the curves versus current density and aperture (d) match well with experiment. Figure Legend: From: Dual-prism coupler for board-level free-space optical interconnects: design and simulations Opt. Eng. 2012;51(4):045401-1-045401-9. doi:10.1117/1.OE.51.4.045401

2. Date of download: 7/2/2016 Copyright © 2016 SPIE. All rights reserved. Applying Eq. (1) at a 40°C case temperature, the time to when 1% of VCSELs in an array will fail is plotted vs. VCSEL resonant frequency. Time to 1% failure is plotted since for chip-to-chip optical interconnects, an array of hundreds is assumed to be the minimal requirement. Even for aggressive VCSEL designs with 5 µm aperture (d), devices in the array are found to fail in less than a year for a 20 GHz resonant frequency. While the absolute values of the curves may change with different designs, their shape will not, and thus it is expected that as data rates increase above 10 Gbit/sec, VCSEL reliability, especially in arrays, will suffer prohibitively. Figure Legend: From: Dual-prism coupler for board-level free-space optical interconnects: design and simulations Opt. Eng. 2012;51(4):045401-1-045401-9. doi:10.1117/1.OE.51.4.045401

3. Date of download: 7/2/2016 Copyright © 2016 SPIE. All rights reserved. Schematic of the dual-prism module. The bold lines and the dashed lines are the paths of the CW light and the modulated light, respectively. Figure Legend: From: Dual-prism coupler for board-level free-space optical interconnects: design and simulations Opt. Eng. 2012;51(4):045401-1-045401-9. doi:10.1117/1.OE.51.4.045401

4. Date of download: 7/2/2016 Copyright © 2016 SPIE. All rights reserved. Dual-prism design rule for horizontal “emission,” plotted as Eq. (3) (solid curve). The lower limit on α is set by the intersection of the dashed curve [Eq. (4)] and the solid curve. Similarly, the upper limit is set by the intersection of the dash-dotted curve [Eq. (5)] with the solid curve. Thus, only solutions in regions II and IV (shaded) are permissible for horizontal emission. Figure Legend: From: Dual-prism coupler for board-level free-space optical interconnects: design and simulations Opt. Eng. 2012;51(4):045401-1-045401-9. doi:10.1117/1.OE.51.4.045401

5. Date of download: 7/2/2016 Copyright © 2016 SPIE. All rights reserved. A lens is used to first focus the light from the VCSEL onto the underlying MQW device. Then another lens is used to collimate the output beam. These lenses are required to increase the link density and the link distance and can be fabricated directly into the prism glass. Figure Legend: From: Dual-prism coupler for board-level free-space optical interconnects: design and simulations Opt. Eng. 2012;51(4):045401-1-045401-9. doi:10.1117/1.OE.51.4.045401

6. Date of download: 7/2/2016 Copyright © 2016 SPIE. All rights reserved. Schematic of the unfolded optical system. This is an approximation since the first n1−n2 refractive interface is actually tilted. R1 and R2 are the radii of curvature of the input and output lenses, respectively. Figure Legend: From: Dual-prism coupler for board-level free-space optical interconnects: design and simulations Opt. Eng. 2012;51(4):045401-1-045401-9. doi:10.1117/1.OE.51.4.045401

7. Date of download: 7/2/2016 Copyright © 2016 SPIE. All rights reserved. Schematic of input (focusing) lens system. Figure Legend: From: Dual-prism coupler for board-level free-space optical interconnects: design and simulations Opt. Eng. 2012;51(4):045401-1-045401-9. doi:10.1117/1.OE.51.4.045401

8. Date of download: 7/2/2016 Copyright © 2016 SPIE. All rights reserved. Schematic of output (collimating) lens system. Figure Legend: From: Dual-prism coupler for board-level free-space optical interconnects: design and simulations Opt. Eng. 2012;51(4):045401-1-045401-9. doi:10.1117/1.OE.51.4.045401

9. Date of download: 7/2/2016 Copyright © 2016 SPIE. All rights reserved. In this simulation a one dimensional VCSEL array with 11 elements illuminates the transmitting DPM. The Tx-DPM is shown on top and the Rx-DPM below. Both the M-MQW and R-MQW devices are 50 ×50 μm2 in size and the link distance simulated is 10 cm. All of the 1 W of optical power launched from the VCSELs is incident on the corresponding M-MQW device and is then incident on the R-MQW device. Figure Legend: From: Dual-prism coupler for board-level free-space optical interconnects: design and simulations Opt. Eng. 2012;51(4):045401-1-045401-9. doi:10.1117/1.OE.51.4.045401

10. Date of download: 7/2/2016 Copyright © 2016 SPIE. All rights reserved. The spots incident on one M-MQW device (a) and the corresponding R-MQW device (b). Both the devices are 50 ×50 μm2 in size and the link distance simulated is 10 cm. Figure Legend: From: Dual-prism coupler for board-level free-space optical interconnects: design and simulations Opt. Eng. 2012;51(4):045401-1-045401-9. doi:10.1117/1.OE.51.4.045401

11. Date of download: 7/2/2016 Copyright © 2016 SPIE. All rights reserved. Simulated lateral and rotational misalignment tolerances of the DPM link. The system has a lateral and a rotational misalignment FWHM tolerance of 616 µm and 1.13 deg, respectively. Figure Legend: From: Dual-prism coupler for board-level free-space optical interconnects: design and simulations Opt. Eng. 2012;51(4):045401-1-045401-9. doi:10.1117/1.OE.51.4.045401

12. Date of download: 7/2/2016 Copyright © 2016 SPIE. All rights reserved. Simulated misalignment tolerances of the DPM link when the VCSEL array is in misalignment with the transmitting DPM. Square markers indicate power incident on the M-MQW device and round markers on the R-MQW device. Dependence of power incident on the modulating and receiver devices on Δz (a) and Δx (b) misalignment of the VCSELs. The same dependence is shown for Δφ (c) and Δθ (d). The directions and angles are indicated in Fig. 9. Figure Legend: From: Dual-prism coupler for board-level free-space optical interconnects: design and simulations Opt. Eng. 2012;51(4):045401-1-045401-9. doi:10.1117/1.OE.51.4.045401

13. Date of download: 7/2/2016 Copyright © 2016 SPIE. All rights reserved. Schematic of envisioned implementation of board-level optical interconnects using the dual-prism optoelectronic free-space transceiver. A microprocessor may have four transceivers around its perimeter communicating with adjacent processors via their transceivers. Figure Legend: From: Dual-prism coupler for board-level free-space optical interconnects: design and simulations Opt. Eng. 2012;51(4):045401-1-045401-9. doi:10.1117/1.OE.51.4.045401