Fiber optic transceiver module having a molded cover in which an optical beam transformer made of an elastomer is integrally formed
View Patent ↗An FOT module is provided that has a molded cover in which an optical beam transformer is integrally formed. The molded cover includes at least a nontransparent molded part that is secured to a mounting structure, such as a molded leadframe or a PCB, on which at least one active optical device is mounted. The material of which the nontransparent molded part is made has a CTE that matches, or nearly matches, the CTE of the body of the mounting structure. Consequently, exposure of the FOT module to temperature variations will not result in delaminations at the interface of the mounting structure and the nontransparent molded part.
1. A fiber optic transceiver (FOT) module comprising:
a mounting structure having a mounting structure body and at least a mounting surface, the mounting structure body having a coefficient of thermal expansion (CTE);
at least a first active optical device mounted on the mounting surface;
a cover secured to the mounting structure and covering said at least one active optical device, the cover comprising a nontransparent molded part having first and second cavities formed therein, the first cavity providing space for at least the first active optical device mounted on the mounting surface of the mounting structure, the nontransparent molded part being nontransparent to a primary wavelength of light used by the FOT module, the nontransparent molded part comprising a material that has a CTE that matches, or substantially matches, the CTE of the mounting structure body, and wherein the cover has an opening formed therein for mechanically coupling an end of an optical waveguide to the cover; and
a transparent elastomeric material disposed in the second cavity, the transparent elastomeric material being transparent to the primary wavelength of light used by the FOT module, wherein the transparent elastomeric material has an elasticity that allows it to expand and contract if the second cavity of the cover expands and contracts, and wherein the second cavity filled with the transparent elastomeric material operates as an optical beam transformer for transforming a light beam and coupling the transformed light beam between the active optical device and the end of the optical waveguide.
2. The FOT module of claim 1 , wherein the nontransparent molded part comprises a plastic material.
3. The FOT module of claim 1 , further comprising a meander structure formed in the cover and connected to the first cavity to help equalize pressure within the first cavity.
4. The FOT module of claim 3 , wherein the first cavity is at least partially filled with a silicone material such that at least some of the silicone material is interposed between the active optical device and the optical beam transformer.
5. The FOT module of claim 1 , wherein the active optical device is an electrical-to-optical (E/O) converter, and wherein the optical beam transformer has a first lens portion positioned in close proximity to the E/O converter and a second lens portion positioned in close proximity to the opening formed in the cover, the first and second lens portions having a common optical axis, and wherein the E/O converter produces light of the primary wavelength, the first lens portion collimating light produced by the E/O converter into a collimated beam of light, the second lens portion receiving the collimated beam of light and focusing the collimated beam of light to a focal point within the opening formed in the cover.
6. The FOT module of claim 1 , wherein the active optical device is an electrical-to-optical (E/O) converter, and wherein the optical beam transformer has a first lens portion positioned in close proximity to the E/O converter, a second lens portion positioned in close proximity to the opening formed in the cover, and at least one tilted reflective surface disposed between the first and second lens portions, wherein the first and second lens portions have first and second optical axes, respectively, that are at non-zero angles to the tilted TIR surface, and wherein the E/O converter produces light of the primary wavelength, the first lens portion collimating light produced by the E/O converter into a collimated beam of light and directing the collimated beam of light along the first optical axis onto the tilted reflective surface, the tilted reflective surface reflecting the collimated beam of light received thereby onto the second lens portion, the second lens portion receiving the collimated beam of light and focusing the collimated beam of light to a focal point within the opening formed in the cover.
7. The FOT module of claim 6 , wherein the non-zero angles are less than 45°.
8. The FOT module of claim 6 , wherein the non-zero angles are greater than 45°.
9. The FOT module of claim 6 , wherein the non-zero angles are 45° or approximately 45°.
10. The FOT module of claim 6 , wherein the non-zero angles are 60° or approximately 60°.
11. The FOT module of claim 1 , further comprising a ferrule secured to the opening formed in the cover, the ferrule being configured to mechanically couple the end of the optical waveguide to the cover.
12. The FOT module of claim 1 , wherein the mounting structure comprises a printed circuit board (PCB).
13. The FOT module of claim 1 , wherein the PCB is a multi-layer PCB.
14. The FOT module of claim 1 , wherein the mounting structure comprises a premolded leadframe.
15. The FOT module of claim 1 , wherein the active optical device is an optical-to-electrical (O/E) converter, and wherein the optical beam transformer has a first lens portion positioned in close proximity to the O/E converter and a second lens portion positioned in close proximity to the opening formed in the cover, the first and second lens portions having a common optical axis, the second lens portion collimating light passing out of the end of the optical waveguide into a collimated beam of light, the first lens portion receiving the collimated beam of light and focusing the collimated beam of light onto the O/E converter, the O/E converter converting the light focused therein into an electrical signal.
16. The FOT module of claim 1 , wherein the active optical device is an optical-to-electrical (O/E) converter, and wherein the optical beam transformer has a first lens portion positioned in close proximity to the O/E converter, a second lens portion positioned in close proximity to the opening formed in the cover, and at least one tilted reflective surface disposed between the first and second lens portions, wherein the first and second lens portions have first and second optical axes, respectively, that are at non-zero angles to the tilted reflective surface, and wherein the second lens portion collimates light passing out of the end of the optical waveguide into a collimated beam of light and directs the collimated beam of light along the second optical axis onto the tilted reflective surface, the tilted reflective surface reflecting the collimated beam of light received thereby onto the first lens portion, the first lens portion receiving the collimated beam of light and focusing the collimated beam of light onto the O/E converter, the O/E converter converting the light focused therein into an electrical signal.
17. The FOT module of claim 16 , wherein the non-zero angles are less than 45°.
18. The FOT module of claim 16 , wherein the non-zero angles are greater than 45°.
19. The FOT module of claim 16 , wherein the non-zero angles are 45° or approximately 45°.
20. The FOT module of claim 16 , wherein the non-zero angles are 60° or approximately 60°.