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Highly efficient surface-emitting semiconductor lasers exploiting quasi-crystalline distributed feedback photonic patterns
摘要: Quasi-crystal distributed feedback lasers do not require any form of mirror cavity to amplify and extract radiation. Once implemented on the top surface of a semiconductor laser, a quasi-crystal pattern can be used to tune both the radiation feedback and the extraction of highly radiative and high-quality-factor optical modes that do not have a defined symmetric or anti-symmetric nature. Therefore, this methodology offers the possibility to achieve efficient emission, combined with tailored spectra and controlled beam divergence. Here, we apply this concept to a one-dimensional quantum cascade wire laser. By lithographically patterning a series of air slits with different widths, following the Octonacci sequence, on the top metal layer of a double-metal quantum cascade laser operating at THz frequencies, we can vary the emission from single-frequency-mode to multimode over a 530-GHz bandwidth, achieving a maximum peak optical power of 240 mW (190 mW) in multimode (single-frequency-mode) lasers, with record slope efficiencies for multimode surface-emitting disordered THz lasers up to ≈570 mW/A at 78 K and ≈720 mW/A at 20 K and wall-plug efficiencies of η ≈ 1%.
关键词: quantum cascade laser,surface-emitting,Quasi-crystal,THz frequencies,Octonacci sequence,semiconductor lasers,distributed feedback
更新于2025-09-23 15:21:01
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U-shaped photonic quasi-crystal fiber sensor with high sensitivity based on surface plasmon resonance
摘要: A U-shaped external photonic quasi-crystal fiber (PQF) sensor based on surface plasmon resonance is proposed for refractive index (RI) sensing. The advantages of sensing with metal/liquid surface plasmon polariton (SPP) mode are summarized. The gold/liquid SPP mode is excited and used for sensing in the U-shaped external PQF, which can detect a small variation of the analyte RI. The maximum sensitivity of the sensor is 33600 nm/RIU, and the average sensitivity is 21643.75 nm/RIU within the detection RI range of 1.420–1.436. The U-shaped PQF sensor will provide a new design idea for the RI sensor with high sensitivity.
关键词: U-shaped photonic quasi-crystal fiber,surface plasmon resonance,refractive index sensing,high sensitivity
更新于2025-09-11 14:15:04