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A sampled-grating distributed Bragg reflector laser module having an integrated multiwavelength locker has been developed and evaluated. The uniquely designed wavelength locker made of thermally controlled etalon has provided uniform wavelength monitoring and very stable wavelength locking in the 188-ITU grid channels (37 nm) with 25-GHz spacing. Over the case temperature from -5°C to 65°C, the laser wavelength was locked within ±0.5 GHz, and the total power consumption of the module was less than 4 W. [ABSTRACT FROM PUBLISHER]

Planar buried heterostructure (PBH) was adopted to fabricate a sampled grating distributed Bragg reflector laser diode (SGDBR-LD) having a low threshold current and a stable fundamental transverse mode. The etching process for butt-coupling was optimized to improve the reproducibility and the uniformity of the butt-coupled waveguide. The maximum output power of the fabricated SGDBR-LD was 20 mW at 200-mA continuous-wave operation at 25°C. The output power was measured 10 and 9 mW higher than those of ridged waveguide (RWG) structure and buried ridge stripe (BRS), and the threshold current was slightly higher than those of RWG and BRS. The spectra of 25 channels spaced 50 GHz within the tuning range of 44.4 nm was obtained by a precise control of SG and phase control currents. The side-mode suppression ratio of more than 35 dB was obtained in the whole tuning range. The output power variation was less than 5 dB, which is 4 dB smaller than that of RWG structure. [ABSTRACT FROM PUBLISHER]

We optimized the etching process for butt coupling to improve the reproducibility and the uniformity of the process for the integrated GaInAsP multiquantum-well laser with a butt-coupled waveguide. Three different ways of etching process were tested, which are reactive ion etching (RIE), RIE followed by a small amount (50 nm thick) of selective wet etching, and RIE followed by an adequate amount (125 nm thick) of selective wet etching. RIE followed by an adequate amount of selective wet etching showed the superior properties to the common expectation on RIE only, giving the measured coupling efficiency 96±1.7% versus 34±8%. The high coupling efficiency and the very small variation across a quarter of a 2-in wafer demonstrate that RIE coupled with an adequate amount of selective wet etching can also replace the conventional process for butt coupling, RIE followed by HBr-based nonselective wet etching, to fabricate high-quality integrated photonic devices. [ABSTRACT FROM PUBLISHER]

In this study, we design a compact terahertz (THz) reflection scanner with a scan rate of 20 frames/s. This scanner is based on a benzocyclobutene-embedded InGaAs Schottky barrier diode detector having a maximum responsivity of 300 V/W at 250 GHz and a minimum noise equivalent power of 38 pW/. With this scanner, details such as sharp head and tail and wrinkled segments in a moving caterpillar are observed. The thin and thick parts of the moving caterpillar that are presented in light gray and dark gray, respectively, on the gray scale are also well distinguished. [ABSTRACT FROM AUTHOR]