Optical module and optical transceiver

An optical transmission device, comprising:

• an optical modulator that is configured to optically modulate light according to an electrical signal;
• a driver that is configured to output the electrical signal;
• and
• a flexible substrate that electrically connects the optical modulator and the driver, wherein
• the flexible substrate includes
• a signal pad at least a part of which is fixed to the driver,
• a ground pad at least a part of which is fixed to the driver,
• a signal line that is formed on a first surface of the flexible substrate and connects the signal pad and the optical modulator, the signal line having a width narrower than the signal pad,
• a ground pattern that is formed on a second surface serving as a rear surface of the first surface,
• a first coverlay including a first protrusion part that is formed on the first surface, covers a region on the flexible substrate where the signal line is disposed, and protrudes at a location where the signal pad is disposed, toward an end part of the flexible substrate on the driver side than the region where the signal line is disposed, and
• a second coverlay including a second protrusion part that is formed on the second surface, protrudes at a location where the signal pad is disposed, toward an end part of the flexible substrate on the driver side, and covers a region on the ground pattern facing at least the signal pad.

An optical reception device, comprising:

• an optical receiver that is configured to convert received light into an electrical signal;
• a signal processor that is configured to perform signal processing on the converted electrical signal;
• and
• a flexible substrate that electrically connects the optical receiver and the signal processor, wherein
• the flexible substrate includes
• a signal pad at least a part of which is fixed to the signal processor,
• a ground pad at least a part of which is fixed to the signal processor,
• a signal line that is formed on a first surface of the flexible substrate and connects the signal pad and the optical receiver, the signal line having a width narrower than the signal pad,
• a ground pattern that is formed on a second surface serving as a rear surface of the first surface,
• a first coverlay including a first protrusion part that is formed on the first surface, covers a region on the flexible substrate where the signal line is disposed, and protrudes at a location where the signal pad is disposed, toward an end part of the flexible substrate on the signal processor side than the region where the signal line is disposed, and
• a second coverlay including a second protrusion part that is formed on the second surface, protrudes at a location where the signal pad is disposed, toward an end part of the flexible substrate on the signal processor side, and covers a region on the ground pattern facing at least the signal pad.