Optical module

1. An optical module, comprising:

an optical subassembly configured to convert at least one of an optical signal or an electrical signal into another one of the optical signal and the electrical signal;

a wiring substrate that has a wiring pattern comprising a connecting portion and is arranged on the optical subassembly so as to be electrically connected thereto; and

a flexible insulating layer formed between the optical subassembly and the wiring substrate,

the optical subassembly comprising:

a conductive stem that has a surface opposed to the wiring substrate, the conductive stem being shaped so that the surface has a through hole opened therein and being connected to a reference potential; and

a signal lead for transmitting a signal, the signal lead passing through the through hole while being electrically insulated from the conductive stem,

the signal lead passing through the flexible insulating layer to be joined to the connecting portion,

the flexible insulating layer being in contact with the connecting portion, the signal lead, and the surface of the conductive stem.

2. The optical module according to claim 1 ,

wherein the wiring substrate comprises an insulating substrate having a thickness corresponding to a distance between a first surface and a second surface of the insulating substrate,

wherein the first surface is opposed to the surface of the conductive stem, and

wherein at least part of the connecting portion is formed on the first surface.

3. The optical module according to claim 2 ,

wherein the connecting portion is formed on the first surface and the second surface so as to pass through the insulating substrate, to thereby form a through-hole via for electrical connection, and

wherein the signal lead is inserted into the through-hole via.

4. The optical module according to claim 2 , wherein the wiring pattern comprises signal wiring connected to the connecting portion, for transmitting the signal, and a plane layer for connection with the reference potential.

5. The optical module according to claim 4 ,

wherein the signal wiring is formed on the second surface, and

wherein the plane layer is formed on the first surface.

6. The optical module according to claim 4 ,

wherein the signal wiring is formed on the first surface, and

wherein the plane layer is formed on the second surface.

7. The optical module according to claim 2 ,

wherein the wiring substrate comprises a protective film for covering the wiring pattern, and

wherein the wiring pattern is formed on the first surface and the second surface.

8. The optical module according to claim 7 , wherein the wiring pattern formed on the first surface overlaps the conductive stem.

9. The optical module according to claim 7 , wherein the wiring pattern formed on the first surface overlaps a region other than the conductive stem.

10. The optical module according to claim 7 , wherein the protective film formed on the first surface overlaps the conductive stem.

11. The optical module according to claim 7 , wherein the protective film formed on the first surface overlaps a region other than the conductive stem.

12. The optical module according to claim 1 , wherein the optical subassembly further comprises a reference lead electrically connected to the conductive stem in order to electrically connect the conductive stem to the reference potential.

13. The optical module according to claim 1 ,

wherein the wiring pattern is electrically connected to the conductive stem on the first surface, and

wherein the conductive stem is electrically connected to the wiring pattern on a side surface of the conductive stem while avoiding the surface.

14. The optical module according to claim 1 ,

wherein the through hole of the conductive stem and the signal lead are electrically insulated from each other with an insulating material,

wherein the insulating material is filled so that a projecting portion is formed that protrudes from the surface of the conductive stem, and

wherein the flexible insulating layer has a recessed portion in contact with the projecting portion.