M. Nesnidal

High continuous wave output power InGaAs/InGaAsP/InGaP diode lasers: Effect of substrate misorientation

3 W cw output power has been obtained from aluminum‐free, strained‐layer double‐quantum well (DQW) InGaAs/InGaAsP/InGaP uncoated, 100‐μm‐wide stripe diode lasers (λ=0.945 μm) grown by low‐pressure MOCVD on exact (100) GaAs substrates. The combination of high‐band‐gap (1.62 eV) InGaAsP confinement layers and the DQW structure provides relatively weak temperature dependence for both the threshold current Ith as well as the external differential quantum efficiency ηd. Furthermore, the series electrical resistance for 100 μm×600 μm stripe‐contact devices is as low as 0.12 Ω. As a result, the power conversion efficiency reaches a maximum of 40% at 8×Ith, and decreases to only 33% at the maximum power (i.e., 3 W) at 28×Ith. Low‐temperature (12 K) photoluminescence measurements of InGaAs/InGaAsP quantum‐well structures exhibit narrow linewidths (<10 meV) for material grown on exact (100) GaAs substrates, while growths on misoriented substrates exhibit linewidth broadening, as a result of ‘‘step bunching.’’ Laser...

High-power single-mode simplified antiresonant reflecting optical waveguide (S-ARROW) distributed feedback semiconductor lasers

Simplified antiresonant-reflective-optical-waveguide distributed-feedback semiconductor lasers based on Al-free InGaAs-InGaAsP-InGaP materials are reported for the first time. Devices with 6.5-/spl mu/m-wide emitting apertures operate single-frequency (/spl lambda/=0.968 /spl mu/m) and single-spatial-mode to 157-mW continuous-wave output power. The full-width at half-maximum of the lateral far-field pattern is 4.5/spl deg/, in excellent agreement with theory. Relative intensity noise values as low as -154 dB/Hz are measured between 500 MHz and 8 GHz.

MOVPE-grown high CW power InGaAs/InGaAsP/InGaP diode lasers

Al-free InGaAs/InGaAsP/InGaP laser structures grown by MOVPE have yielded new records in performance. CW front-facet-emitted powers of 5.8 W are achieved from optimized double-quantum-well lasers with 100 μm wide stripes and 1 mm long cavity lengths. Devices with a 0.5 mm cavity length exhibit total power conversion efficiencies as high as 59%. A novel facet passivation technique, consisting of laser-assisted deposition of ZnSe, is shown to increase the COD level by 50%. Single-mode, CW output powers of 400 mW are obtained from triple-core ARROW lasers fabricated by a two-step MOVPE growth process.

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.

Single-frequency, single-spatial-mode ROW-DFB diode laser arrays

Single-frequency, stable single-spatial-mode operation from large-aperture (40-60 /spl mu/m) index-guided devices is demonstrated from resonant antiguided phase-locked InGaAs-InGaP-GaAs diode-laser arrays incorporating 2nd-order distributed-feedback gratings (i.e., ROW-DFB arrays). The devices operate in a single-spatial-mode up to 3.6/spl times/threshold, and truly single-mode (i.e., single-spatial-mode and single-frequency) up to 2/spl times/threshold, For 40 (60)-/spl mu/m-aperture 10-element arrays, the beam pattern is in-phase and diffraction-limited with 70% (75%) of the power residing in the main lobe. Single-frequency operation is obtained from 9640-9652 /spl Aring/, over a temperature range of approximately 20/spl deg/C, side-mode suppression ratios /spl ges/20 dB are recorded up to 2/spl times/threshold.

Distributed-feedback grating used as an array-mode selector in resonant antiguided diode laser arrays: effects of the mirror facet position with respect to the grating

In resonant and nearly resonant antiguided arrays (ROW arrays), if the grating is located below the active region, a distributed-feedback (DFB) grating can function as a selector for the in-phase array mode in addition to its role as a frequency discriminator. Threshold current densities are calculated for competing (lateral) spatial modes in AR/HR coated 10- and 20-element arrays incorporating lower gratings (ROW-LDFB arrays). Calculations include the effects of random facet locations relative to the grating phase. The threshold current density, J/sub th/, of the in-phase mode and its discrimination, /spl Delta/J/sub th/, against other (array) spatial modes vary with facet location. For 20 (10) elements, J/sub th//spl ap/350-525 (400-550) A/cm/sup 2/ and /spl Delta/J/sub th/ reaches a maximum of 55 (58) A/cm/sup 2/ for 0.01/0.95 AR/HR-coated 350 /spl mu/m-long devices. For 10-element arrays, the probability of in-phase operation is approximately 50%; for 20-element arrays, the probability is 100%. Preliminary experimental results from 20-element nonresonant devices with uncoated facets are near diffraction-limited beams and nearly single-frequency operation to 250 mW.

Distributed-feedback grating used as a lateral-mode selector in phase-locked antiguided arrays

We show here, for the first time, that a distributed-feedback (DFB) grating can act as a lateral-mode discriminator if located below the active region of a phase-locked antiguided array. Spatial-mode selection from such a lower-DFB (LDFB) grating in a resonant antiguided structure (ROW-LDFB) relies on the fact that the optical field distribution below the active region is strongly array-mode dependent. In particular, it is shown that at and near resonance a ROW-LDFB structure strongly favors resonant-mode oscillation, while suppressing oscillation of high-order modes. ROW-LDFB devices thus accomplish both spatial- and frequency-mode selection in a single structure. Furthermore, for effective intermodal discrimination, there is no need for interelement loss or Talbot-type filters, thus eliminating all potential sources of self-pulsations.

10 W near-diffraction-limited pulsed power from Al-free phase-locked antiguided arrays

10 W peak-pulsed power emitted in a beam pattern 2/spl times/diffraction limit is obtained from a 40-element, 200 /spl mu/m-aperture Al-free phase-locked antiguided array (/spl lambda/=0.98 /spl mu/m). 60% of the power resides in the central lobe, and the differential quantum efficiency is 54 % for 1 mm-long devices. The devices were fabricated by a two stage self-aligned etch-and-regrowth process. In the first stage, the strained InGaAs double quantum well (DQW) active region and GaAs guide layer were grown by low-pressure MOCVD. High-index GaAs material was then selectively removed to define the element regions, after which the p-InGaP cladding and GaAs contact layers were regrown.

High-power, narrow-beam, single mode ARROW-type semiconductor diode lasers

Summary form only given. By increasing the interelement optical absorption loss in 0.98 /spl mu/m-wavelength three-core ARROW-type diode lasers we have achieved, from 20 /spl mu/m-aperture devices, a diffraction-limited beam pattern to 0.55 W peak-pulsed power with 78% of the light in the central lobe, and near diffraction-limited operation to 0.7 W.

High CW output power InGaAs/InGaAsP/InGaP diode lasers: effect of substrate misorientation

Summary form only given. 3 W CW output power is obtained from InGaAs-InGaAsP-InGaP uncoated, 100-/spl mu/m-wide-stripe, quantum well diode lasers grown by low-pressure MOCVD on exact (100) GaAs substrates. Lasers grown on misoriented substrates exhibit increased temperature sensitivity of threshold and differential quantum efficiency.