Two section blue laser diode with reduced output power droop

Abstract

A III-V nitride blue laser diode has an amplifier region and a modulator region. The amplifier region has a constant current to keep the region near the lasing threshold. The modulator region has a small varying forward current or reverse bias voltage which controls the light output of the laser. This two section blue laser diode requires much lower power consumption than directly modulated lasers which reduces transient heating and “drooping” of the light output.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to a blue laser diode and, more particularly, to a two section blue laser diode with an amplifier region and a modulator region to reduce power output variations.[0002]Solid state lasers, also referred to as semiconductor lasers or laser diodes, are well known in the art. These devices generally consist of a planar multi-layered semiconductor structure having one or more active semiconductor layers bounded at their ends by cleaved surfaces that act as mirrors. The semiconductor layers on one side of the active layer in the structure are doped with impurities so as to have an excess of mobile electrons. The semiconductor layers on the other side of the active layer in the structure are doped with impurities so as to have a deficiency of mobile electrons, therefore creating an excess of positively charged carriers called holes. Layers with excess electrons are said to be n-type, i.e. negative, while layers with excess hole...

AI Technical Summary

Benefits of technology

[0020]According to the present invention, an III-V nitride blue laser diode has an amplifier region and a modulator region. The amplifier region has a constant current to keep the region near the lasing threshold. The modulator region has a small varying forward current or reverse bias voltage which controls the light output of the laser. This two section blue laser diode requires much lower power consumption than directly modulated lasers which reduces transient heating and “drooping” of the light output.

[0022]Since only a small section of the laser diode is used to control the output power, the resulting lower capacitance should also be beneficial for achieving higher modulation speeds.

Problems solved by technology

When a laser device is switched from the OFF to the ON state, transient heating, or heating that changes over time, can cause the light output of AlGaInN laser diodes to drop significantly.

This increased temperature results in a decreased output power for the AlGaInN laser diode.

Thermal fluctuations are especially deleterious to maintaining constant optical power output, especially during pulsed modulation.

This sustained temperature increase results in a further decrease in the output pulse obtained with a constant level of input current.

Due to the poor thermal conductivity of the sapphire substrate and the relatively high electric power consumption of III-nitride baser laser devices, transient heating is an issue to AlGaInN devices.

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