David V. Forbes

Performance and reliability of ARROW single-mode and 100-μm laser diode and the use of NAM in Al-free lasers

While high-powered broad area lasers emitting between 915nm and 975nm are required for pumping Er+ and Yb+ doped dual clad fiber lasers and amplifiers, the single mode 980nm lasers are used for pumping EDFAs. We report on the performance and a systematic reliability assessment of Alfalight’s first generation Al-free multimode laser diodes with 100µm aperture and 2mm cavity length emitting between 950nm and 980nm. Data from 120 devices in five different multi-cell conditions show median life due to wear-out failure to be over 75.5 years. In addition, over 1,307,600 device-hours of accelerated lifetest data at 3A and a 70C heatsink temperature have been accumulated demonstrating 55 FIT (60% confidence level) at a 2W and 25C operation condition. We also present results from a packaged multimode diode laser with wavelength stabilized at 972nm with a spectral FWHM of 0.3nm demonstrating the capability to use such a device for pumping Er+ and Yb+ doped fibers near the more efficient 975nm portion of the absorption spectrum. Advances made in anti-resonant reflective optical waveguide (ARROW) type single mode diode lasers and the advantages over the conventional positive index guided ridge waveguide type lasers will be discussed. Single mode operation of ARROW single mode laser up to 450mW (ex-facet) was achieved. Results from the facet passivation studies showing successful implementation of non-absorbing mirror (NAM) due to quantum well intermixing using Si implantation in Al-free diode lasers will also be discussed. We have demonstrated reliable operation in excess of 5500 hours in index-guided Al-free diode lasers at a constant power of 500mW at a heatsink temperature of 25C.

Large spatial mode, single frequency semiconductor lasers using two dimensionalgratings

We demonstrate single mode operation of laser diode cavities up to 200|iim wide using 2-D Bragg gratings for simultaneous longitudinal and lateral mode control.

Semiconductor optical modulators for high-performance analog rf photonic links and signal processing

Semiconductor based optical modulators offer flexibility in providing engineerable optical transfer characteristics that can target specific applications. Use of quantum well active regions provides the capability of efficient and linearized transfer characteristics that can benefit analog RF systems in terms of link gain, noise figure and spur free dynamic range. We present experimental results demonstrating the potential for improvements in modulator linearity and efficiency using quantum well based Mach-Zehnder modulators.

High power, high-frequency waveguide photodetectors

Optical RF analog applications are generating great interest for a number of reasons including the flexibility of fiber optic systems and the enormous RF signal processing capability offered by photonics. A limitation to the insertion of RF photonics has been the availability of high performance photonic components that can deliver on the advantages offered by photonic systems. In this paper we will discuss test results of InGaAsP-InP based waveguide photodetectors targeting optical RF analog applications.

Broadband high-power photodetector arrays for photonically implemented phased-array antenna architectures

The authors present a monolithically integrated photodetector array combiner approach that operates over an extremely wide RF bandwidth. These arrays are suitable for coherent RF signal combining applications such as optically controlled phased array radar. The approach consisted of a monolithically integrated array of high-power, wideband photodetectors distributed along an RF transmission line resulting in a low power consumption, broadband, high power handling optical-to-RF combiner, The authors demonstrated a 4-element photodetector array with a small-signal 3dB bandwidth of 34 GHz. RF models were developed and calibrated to the measured results to predict the performance of larger arrays. The models predict than an 8-, 16-, and 48-element array would have a small-signal 3dB bandwidth of 25 Ghz, 15.7GHz, and 5.8GHz respectively. These arrays showed a reasonable amount of robustness to variations and/or errors in the time delays of the input optical feed network suggesting that implementation outside the laboratory should be practical.