BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a laser device and a transmitter.

Description of the Background Art

Japanese Patent Laying-Open No. 2017-228889 discloses an underwater communication system in which two communication devices, using 450 nm blue laser diodes having good transmission characteristics in the water, communicate with each other by exchanging laser light beams. The two communication devices each have a transmitter which transmits laser light to a peer communication device, and a receiver which receives laser light transmitted by the peer communication device.

The transmitter includes a modulation device, a laser driver, and a semiconductor laser. The modulation device outputs a modulated wave signal to a laser driver. The laser driver drives the semiconductor laser, using a current dependent on the modulated wave signal and power from a power supply device.

SUMMARY OF THE INVENTION

In the transmitter, an electric line is disposed between the laser driver and the semiconductor laser, via which a current is supplied to the semiconductor laser. The longer the length of the electric line, the greater the inductance the electric line has, ending up with an increased voltage drop in the electric line. If a voltage applied by the laser driver is increased in order to compensate for the voltage drop at the electric line, a concern is raised that high speed modulation of laser light becomes difficult. In order to reduce the voltage drop at the electric line, desirably, the length of the electric line is reduced by disposing the laser driver proximate to the semiconductor laser.

In contrast, a large current needs to pass through the semiconductor laser in order to output high power laser light. This also increases generation of heat by the semiconductor laser, requiring the installation of a cooler as a measure to address the heat dissipation by the semiconductor laser. Due to this, the laser driver is blocked by the cooler, limiting in disposing the laser driver proximate to the semiconductor laser. As a result, reduction in the length of the electric line is also limited.

Thus, the present embodiment provides a laser device and a transmitter which allow high speed modulation of a semiconductor laser, while ensuring the cooling performance of the semiconductor laser.

A laser device according to a first aspect of the present invention includes: a semiconductor laser; at least one driver that supplies the semiconductor laser with a current; a modulator that modulates the current to be supplied to the semiconductor laser; and at least one electric line for conveying the current from the at least one driver to the semiconductor laser. The at least one electric line is a wire in a form of a tape, and includes a first conductive layer, a second conductive layer, and an insulating layer that are extending in a longitudinal direction of the wire. The first conductive layer and the second conductive layer are stacked, with the insulating layer in between, in the direction of thickness of the wire.

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

