We report on terahertz quantum-cascade lasers (THz QCLs) based on first-order lateral distributed-feedback (lDFB) gratings, which exhibit continuous-wave operation, high output powers (>8 mW), and single-mode emission at 3.3-3.4 THz. A general method is presented to determine the coupling coefficients of lateral gratings in terms of the coupled-mode theory, which demonstrates that large coupling strengths are obtained in the presence of corrugated metal layers. The experimental spectra are in agreement with simulations of the lDFB cavities, which take into account the reflective end facets.
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| http://dx.doi.org/10.1364/OE.20.011207 | DOI Listing |
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- A coupled distributed feedback (DFB) laser system using AlGaAs/GaAs semiconductor is developed, emitting light near 820 nm and utilizing a shared Bragg grating for dual-frequency operation.
- The system achieved dual-mode operation with a 4.2 nm wavelength difference, resulting in a 1.86 THz beat frequency and producing 14.7 mW output power at a current of 195 mA.
- This new design simplifies the manufacturing process for dual-mode DFB lasers and enhances compatibility with high-frequency photodetectors, while potentially allowing for tunable beat frequencies.
A novel, to the best of our knowledge, broad-area distributed feedback laser with high-order surface curved gratings has been fabricated based on standard near ultraviolet lithography. The characteristics of increasing output power and mode selection are achieved simultaneously by using a broad-area ridge as well as an unstable cavity structure composed of curved gratings and a high-reflectivity coated rear facet. Suppression of high-order lateral modes is realized by setting current injection/non-injection regions and asymmetric waveguides.
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