An etch-free and cost-effective deposition and patterning method to fabricate mid-infrared chalcogenide glass waveguides for chemical sensing applications is introduced. As(2)S(3) raised strip optical waveguides are produced by casting a liquid solution of As(2)S(3) glass in capillary channel molds formed by soft lithography. Mid-IR transmission is characterized by coupling the output of a quantum cascade (QC) laser (lambda = 4.8 microm) into the 40 microm wide by 10 microm thick multi-mode waveguides. Loss as low as 4.5 dB/cm is achieved using suitable substrate materials and post-processing. Optical absorption and surface roughness measurements indicate that the solution-processed films are of sufficient quality for optical devices and are promising for further development of waveguide-based mid-IR elements.
Articles you may be interested inLow divergence single-mode surface emitting quantum cascade ring lasers Appl. Phys. Lett. 93, 161101 (2008); 10.1063/1.3000630 High-power, continuous-wave operation of distributed-feedback quantum-cascade lasers at λ ∼ 7.8 μ m Appl. Phys. Lett. 89, 251119 (2006); 10.1063/1.2408639 Room-temperature, high-power, and continuous-wave operation of distributed-feedback quantum-cascade lasers at λ ∼ 9.6 μ m Appl. Phys. Lett. 88, 201114 (2006); 10.1063/1.2205730High-power, room-temperature, and continuous-wave operation of distributed-feedback quantum-cascade lasers at λ ∼ 4.8 μ m Appl. Phys. Lett.
We characterize the performance of a quantum well infrared photodetector (QWIP), which is fabricated as a photonic crystal slab (PCS) resonator. The strongest resonance of the PCS is designed to coincide with the absorption peak frequency at 7.6 µm of the QWIP. To accurately characterize the detector performance, it is illuminated by using single mode mid-infrared lasers. The strong resonant absorption enhancement yields a detectivity increase of up to 20 times. This enhancement is a combined effect of increased responsivity and noise current reduction. With increasing temperature, we observe a red shift of the PCS-QWIP resonance peak of -0.055 cm(-1)/K. We attribute this effect to a refractive index change and present a model based on the revised plane wave method.
We describe the fabrication and operation of vertically emitting distributed feedback quantum cascade ring lasers operating in the terahertz frequency range. A twofold increase in radiation efficiency is observed as compared to Fabry–Pérot lasers. The emitters exhibit a robust single-mode operation around 3.2 THz with a side mode suppression ratio higher than 30 dB. Modal and threshold characteristics are investigated by performing finite element simulations with results in good agreement with experiments. The ring-shaped resonator facilitates beam collimation which results in a symmetric far-field profile.
We describe the fabrication and operation of surface emitting second-order distributed feedback quantum cascade ring lasers. The devices exhibit single-mode emission at a wavelength of 3.95μm with a side mode suppression ratio of 25dB. A linear tuning coefficient of 0.13cm−1∕K is observed. A single longitudinal mode in the ring shaped resonator results in a highly symmetric far-field pattern and a low beam divergence, represented by a full width at half maximum of ∼3°. Based on these characteristics the presented compact coherent light source may find its way into today’s midinfrared spectroscopy applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.