Mitsuru Sugo

High-power highly reliable 1.02-1.06-/spl mu/m InGaAs strained-quantum-well laser diodes

By growing the InGaAs active layer at temperatures lower than in conventional growth, we extended the lasing wavelength and presented the high reliability in InGaAs strained-quantum-well laser diodes. Equivalent I-L characteristics were obtained for 1.02-, 1.05-, and 1.06-/spl mu/m laser diodes with a cavity length of 1200 /spl mu/m. Maximum output power as high as 800 mW and fundamental transverse mode operation at up to 400 mW were obtained at 1.06 /spl mu/m and an 1800-/spl mu/m cavity. Stable operation was observed for over 14 000 h under auto-power-control of 225 mW at 50/spl deg/C for the 1.02-, 1.05-, and 1.06-/spl mu/m lasers with a 900-/spl mu/m cavity.

Failure analysis of InGaAs/GaAs strained-Layer quantum-well lasers using a digital OBIC monitor

The mechanisms that cause the sudden failure of InGaAs/GaAs strained-layer quantum-well lasers (LD) are analyzed by monitoring an optical beam-induced current (OBIC). Statistically, the LDs that suddenly fail have different n-OBIC/sub ridge/ intensity profiles (p-n junction OBIC under the ridge normalized by that under the electrode) from LDs with conventional catastrophic optical damage. It appears that dislocations are generated in the vicinity of an antireflection (AR) facet and extend to the AR facet, and meltdown finally occurs there. The suppression of dislocation generation around the AR facet is important in regards to preventing sudden failure.

Degradation behavior in InGaAs/GaAs strained-quantum well lasers

Facet degradation mechanisms of a 980-nm InGaAs/GaAs strained-quantum well laser are analyzed by monitoring the optical-beam induced current. It is clarified that the behavior of defects around the facets govern the long-term stability as well as catastrophic-optical damage generation during operation.

Highly Reliable 1.5-

The degradation behavior of 1.5-mum uncooled distributed feedback (DFB) lasers with a semi-insulating buried heterostructure during constant-power aging is investigated. Long-term stability is achieved by suppressing the t0.5 deterioration in the current increase rate (second-stage degradation). The improvement in reliability is attributed to the fact that some defects on the grating interface are simultaneously suppressed by the mutual diffusion that occurs when growing the SI-InP layer. We realized a DFB laser with high reliability (< 1000 failure digits) at 95 degC that is capable of error-free 2.5-Gb/s 80-km transmission at -20degC to 100 degC

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We investigated the degradation behavior of distributed feedback lasers by employing the optical-beam-induced current measurement technique. We showed that the degradation mechanism is governed by diffused defects at the waveguide other than those in the vicinity of the antireflection facet. In addition, we found that a diffused source is probably generated in the upper InP cladding layer above the grating during the growth of the upper InP cladding layer.

DFB Laser With High-Mesa SIBH Structure

We describe a highly efficient coupling of up to 78% into a single mode fiber (SMF) by utilizing a low-divergence-angle InGaAs-AlGaAs laser and a new high-NA aspheric lens, resulting in the coupled optical output of over 300 mW with a kink-free performance. The kink-free 300 mW of fiber-coupled power is the largest power reported from a diode laser wavelength stabilized using a fiber Bragg grating. A 3% fiber Bragg grating makes the optical output stabilize at a wavelength of 1.016 /spl mu/m for an optical output power up to 310 mW and without any distinct decrease of the optical output. The coupling tolerance for lateral offsets is improved by utilizing a thermal-diffused expanded-core technique even in the case of using a high-NA coupling aspheric lens. We have also achieved a 300-mW fiber-coupled wavelength-stabilized InGaAs-AlGaAs semiconductor laser butterfly module using a fiber Bragg grating.

Analysis of Wear-Out Degradation of a DFB Laser Using an Optical-Beam-Induced Current Monitor

The degradation behavior of 2-mum wavelength distributed feedback lasers with a p- and n-type InP buried heterostructure during constant-power aging is investigated. The degradation mechanism is governed by diffused defects with a parallel direction in the crystal plane. Furthermore, it is clarified that the epitaxial layers on the mesa affect both first- and second-stage degradations.

Improved coupling efficiency of a strained InGaAs-AlGaAs quantum-well laser into a fiber Bragg grating

Reliability of a Fabry–Perot laser diode (FP-LD) that was developed for use in the bi-directional optical subassembly of access networks was investigated. Stable operation, which was closely related to the wear-out degradation, was confirmed from the results of an accelerated aging test at 85 °C, and a lifetime of over 2×105 h was estimated. To examine the behavior of the wear-out degradation in the FP-LD, we employed an optical-beam-induced-current (OBIC) analysis. From the results of the OBIC analysis, we found that large degradation occurs in the SCH layer rather than in the active layer in the early stage of the FP-LDs life.

Degradation Analysis of 2-

We have achieved a DFB laser with high reliability (<1000 FlTs) at 95/spl deg/C that is capable of error-free 2.5 Gbps 80 km transmissions at -20 to 100/spl deg/C. Long-term stability has been achieved by suppressing the second stage degradation.

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We demonstrate reflectivity adjustment of a film-coated laser facet using ablation etching. The lasing is restrained by laser ablation etching of the facet film of a semiconductor laser and starts again with additional laser ablation etching. The laser ablation etching is useful not only for identifying more than /spl lambda//sub 0//(4n/sub film/) thickness of the coated film but also for adjusting facet coating thickness.