High Temperature Uncooled Lasers

An uncooled laser transmitter is cheaper and more reliable than a thermo-electrically cooled laser transmitter because of its simplicity in packaging. A low-cost, highly-reliable uncooled laser may have a strong influence on pushing fiber deployment closer to the home. For loop applications, the laser transmitter must operate reliably over the temperature range from -40 to 85°C. It is rather difficult to make high performance uncooled lasers in the long wavelength region (1.3-1.55 μm) using the conventional GaxIn1-xASyP1-y/InP materials system because the laser temperature performance suffers from Auger recombination in the low bandgap material and poor electron confinement resulting from the small conduction band offset (ΔEc=0.4ΔEg). We will discuss the design of uncooled lasers to minimize the changes in both threshold current and slope efficiency over the temperature range from -40 to 85 °C. To prevent carrier overflow under high-temperature operation, the electron confinement energy is increased by using the AlxGayIn1-x-yAs/InP materials system instead of the conventional GaxIn1-xASyP1-y/InP materials system. Experimental results of the AlxGayIn1-x-yAs/InP strained quantum well lasers show superior high temperature performances as discussed below.