High-performance GaInNAsSb/GaAs lasers at 1.5 um

Abstract

We achieved 1.5-µm CW SQW GaInNAsSb lasers with GaNAs barriers grown by MBE on GaAs substrates with typical room temperature threshold densities below 600A/cm 2 , external quantum efficiencies above 50%, and output powers exceeding 200mW from both facets for 20x1222µm devices tested epitaxial-side up. In pulsed mode, 450A/cm 2 , 50%, and 1100mW were realized. Longer devices yielded over 425mW of total CW power and thresholds below 450A/cm 2 . These results are comparable to high quality GaInNAs/GaAs lasers at 1.3µm. Z-parameter measurements revealed that these improvements in the performance metrics of approximately 40-60% over previous results are primarily due to reduced monomolecular recombination.The large differential gain of GaInNAsSb/GaNAs/GaAs lasers at 1.5µm of approximately 1.2x10 -15 cm 2 was mostly squandered in previous devices due to large quantities of monomolecular recombination. The characteristic temperatures for threshold current, T 0 , and for efficiency, T 1 , were 66K and 132K, respectively. These reduced values, compared to prior measurements of 106K and 208K, respectively, indicate carrier leakage. Since monomolecular recombination is temperature insensitive, the temperature stability of device operation was adversely affected.

The opportunities, successes and challenges for GaInNAsSb

“…This is clearly illustrated in the characterization of recombination mechanisms using the Z-parameter, which is defined as the derivative of the log of the total laser current divided by the derivative of the square root of measured spontaneous emission [28,29] Z ¼ dðlnðIÞ…”

“…11. Z-parameter extracted from measured spontaneous emission as a function of bias current for prior devices (no plasma source bias and GaNAsSb barriers) and newest devices (plasma source bias and GaNAs barriers) [29]. lasers which operated at wavelengths from 1.49 to 1.51 mm.…”