Single-mode interband cascade laser based on V-coupled cavity with 210 nm wavelength tuning range near 3 µm.

Interband cascade lasers (ICLs) are efficient and compact mid-infrared (3-5 µm) light sources with many applications. By enhancing the coupling coefficient and using a type-I ICL wafer, single-mode ICLs were demonstrated based on V-coupled cavity with significantly extended tuning range and with a side mode suppression ratio (SMSR) exceeding 35 dB in continuous wave operation near 3 µm. A V-coupled cavity ICL exhibited a wavelength tuning up to 67 nm at a fixed temperature, and the total tuning range exceeds 210 nm when the heat sink temperature is adjusted from 80 to 180 K.

Mid-infrared widely tunable single-mode interband cascade lasers based on V-coupled cavities.

We demonstrate widely tunable single-mode V-coupled-cavity lasers emitting at wavelengths near 3 µm based on a type-II interband cascade (IC) structure. The mode selection is achieved using a half-wave V-coupler designed for the IC structure in the mid-infrared range. The laser waveguides and cavity structure are deeply etched in a single etching step, without any grating.

[Cadmium adsorption by biochar prepared from pyrolysis of silk waste at different temperatures].

In this study, biochars (BC300, BC500 and BC700) were produced from silk waste through pyrolysis under oxygen-limited condition at 300, 500 and 700 ℃, respectively. The physicochemical properties of biochar were detected by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometer (XRD) and specific surface area analyzer. The Cd adsorption capacities of biochars were investigated.

Application of CdSe nanoparticle suspension for developing latent fingermarks on the sticky side of adhesives.

Nanometer-sized fluorescent particles were synthesized in an aqueous solution using TGA (mercaptoacetic acid) as the stabilizer. The prepared solution was characterized by fluorescence spectroscopy and applied for detection of latent fingermarks on adhesives. The effects of stabilizer, precursor, pH value, the concentration of cadmium ion and shell structure on fluorescence were also discussed.

Dual interband cascade laser based trace-gas sensor for environmental monitoring.

The development of an interband cascade laser (ICL) based spectroscopic trace-gas sensor for the simultaneous detection of two atmospheric trace gases is reported. The sensor performance was evaluated using two ICLs capable of targeting formaldehyde (H2CO) and ethane (C2H6). Minimum detection limits of 3.

Aircraft and balloon in situ measurements of methane and hydrochloric acid using interband cascade lasers.

Aircraft and balloon in situ measurements of CH4 and HCl using cw distributed feedback (DFB) interband cascade (IC) lasers are reported. In the stratosphere and upper troposphere, sensitivity toward CH4 and HCl is better than 10 ppbv (1 s) and 90 pptv (50 s), respectively. These are the first flight measurements of trace gas-phase species using cw DFB IC lasers.

Multiwavelength discrimination and measurements of a two-gas mixture by use of a broadly tunable mid-infrared semiconductor laser.

Spectroscopic detection of gases can be achieved by measuring a few species-specific absorption lines, requiring very accurate wavelength control. Alternatively, it can be achieved by using many wavelengths spread over a wide range; each wavelength need not be optimal spectroscopically, but all collectively form a unique fingerprint for the species of interest. Statistical regression can be used to quantify their concentrations.