Optical module

1. An optical module comprising:

a conductive block with a first surface and a second surface, the conductive block having some through holes extending therethrough between the first surface and the second surface;

some lead pins including a signal lead pin, the lead pins fixed inside the respective through holes and insulated from the conductive block;

a thermoelectric cooler with an upper surface and a lower surface, the lower surface fixed to the first surface of the conductive block, the thermoelectric cooler having a Peltier device therein configured to transfer heat between the upper surface and the lower surface;

a metal layer laminated on the upper surface of the thermoelectric cooler;

a ground wire connecting the first surface of the conductive block and the metal layer;

a photoelectric device adapted to convert an optical signal and an electrical signal at least from one to another;

a mounting substrate on which the photoelectric device is mounted, the mounting substrate fixed to the upper surface of the thermoelectric cooler with at least the metal layer interposed therebetween, the mounting substrate having a first wiring pattern electrically connected to the photoelectric device;

a relay substrate having a second wiring pattern electrically connected to the signal lead pin; and

a signal wire configured to connect the first wiring pattern and the second wiring pattern.

2. The optical module according to claim 1 , wherein

the mounting substrate has a mounting surface on which the photoelectric device is mounted, and

the upper surface of the thermoelectric cooler and the mounting surface face in respective directions intersecting with each other.

3. The optical module according to claim 2 , wherein the photoelectric device is arranged such that an optical axis extends in a direction parallel to the mounting surface.

4. The optical module according to claim 1 , further comprising a support block interposed between the metal layer and the mounting substrate.

5. The optical module according to claim 4 , wherein the support block has a cuboid shape, the cuboid shape having a surface fixed to the metal layer and another surface fixed to the mounting substrate, which are adjacent to each other.

6. The optical module according to claim 4 , wherein the support block is made of metal.

7. The optical module according to claim 4 , wherein the support block is made of non-metal.

8. The optical module according to claim 1 , wherein

the metal layer is part of a metal block interposed between the upper surface of the thermoelectric cooler and the mounting substrate,

the metal block has a projection integral with the metal layer, and

the mounting substrate is mounted on the projection.

9. The optical module according to claim 1 , wherein

the signal lead pin is adapted to single-ended driving of the photoelectric device, and

the first wiring pattern has a ground electrode to which a back side of the photoelectric device is bonded.

10. The optical module according to claim 1 , wherein

the signal lead pin is a pair of signal lead pins adapted to drive the photoelectric device by differential signals,

the first wiring pattern includes a pair of first differential signal lines, and

the second wiring pattern includes a pair of second differential signal lines bonded to the respective pair of signal lead pins.

11. The optical module according to claim 1 , wherein the ground wire is two or more ground wires.

12. The optical module according to claim 1 , wherein

the conductive block has a pedestal portion integral with the first surface, and

the relay board rests on the pedestal portion.

13. The optical module according to claim 1 , further comprising a thermistor mounted on the metal layer.