Akihiko Kasukawa

Recorded Low Power Dissipation in Highly Reliable 1060-nm VCSELs for “Green” Optical Interconnection

1060-nm VCSELs with low power dissipation and high reliability are demonstrated. We designed 1060-nm VCSELs with double intracavity structure to achieve high reliability and low power dissipation for the optical interconnection. We performed evaluations of an error-free 10-Gbps operation at low bias current, and the recorded low power dissipation per data rate of 0.14 mW/Gbps was achieved. Even though the modulation amplitude of the input signal was as small as 75 mVp-p, the extinction ratio of 6.5 dB was observed. From accelerating aging tests with 4898 devices, no random failure was observed, and high reliability of 30 failures in term (FITs)/channel with a confidence level of 90% was achieved.

High-performance CW 1.26-/spl mu/m GaInNAsSb-SQW ridge lasers

Long wavelength GaInNAsSb-SQW lasers and GaInAsSb-SQW lasers that include a small amount of Sb were successfully grown by gas-source molecular beam epitaxy (GSMBE). We confirmed that Sb reacts in a highly strained GaInAs-GaAs system and GaInNAs-GaAs system like a surfactant, which increases the critical thickness at which the growth mode changes from two-dimensional (2-D) growth to three-dimensional (3-D) growth. The lasers were processed into ridge lasers. The GaInNAsSb lasers oscillated under continuous-wave (CW) operation at 1.258 /spl mu/m at room temperature. The low CW threshold current of 12.4 mA and high characteristic temperature (T/sub c/) of 157 K were obtained for GaInNAsSb lasers, which is the best result for GaInNAs-based narrow stripe lasers. Further, the GaInNAsSb laser oscillated under CW conditions over 100/spl deg/C. On the other hand, GaInAsSb lasers oscillated under CW operation at 1.20 /spl mu/m at room temperature. The low CW threshold current of 6.3 mA and high characteristic temperature (T/sub c/) of 256 K were obtained for GaInAsSb lasers, which is also the best result for 1.2-/spl mu/m-range highly strained GaInAs-based narrow stripe lasers. We can say that GaInNAsSb lasers are very promising material for realizing an access network. Further, the differential gain of GaInNAs-based SQW lasers was estimated for the first time. GaInNAsSb-SQW lasers have the extremely large differential gain of 1.06-10/sup -15/ cm/sup 2/ in spite of the single-QW lasers; therefore, GaInNAsSb lasers are also suitable for high-speed lasers in the long wavelength region.

Effects of well number in 1.3-/spl mu/m GaInAsP/InP GRIN-SCH strained-layer quantum-well lasers

Effects of well number in 1.3-/spl mu/m GaInAsP/InP GRIN-SCH compressively strained-layer quantum-well lasers were investigated from the viewpoint of the crystal quality of the strained-layer quantum wells and low threshold current operation at high temperature. As a result, we find that the optimum well number that gives the minimum threshold current increases with operating temperature and it was limited to the degradation of crystal quality of the quantum wells due to the critical thickness. A very high CW operating temperature of 170/spl deg/C was obtained. A very high output power of over 300 mW was also achieved. >

1.3 μm InAsyP1−y/InP strained‐layer quantum well laser diodes grown by metalorganic chemical vapor deposition

We report on the metalorganic chemical vapor deposition (MOCVD) growth of InAsyPl1−y/InP strained layer quantum wells and the successful lasing of novel InAsyP1−y/InP strained layer quantum well laser diodes at 1.3 μm for the first time. Full width at half maximum of room temperature photoluminescence was as narrow as 30.1 meV with a peak wavelength of 1.29 μm. A very low threshold current density of 0.45 kA/cm2 was obtained on broad contact lasers with a cavity length of 900 μm.

GaInAsP/InP Semiconductor Multilayer Reflector Grwon by Metalorganic Chemical Vapor Deposition and its Application to Surface Emitting Laser Diode

A GaInAsP/InP multilayer reflector was fabricated by low pressure metalorganic chemical vapor deposition. Peak reflectivity of as high as 0.98 was obtained, which was in good agreement with the calculated value. This multilayer reflector was applied to a 1.5 µm GaInAsP/InP vertical cavity surface emitting laser diode, and room temperature pulsed oscillation was achieved for the first time with a threshold current density of 124 kA/cm2.

Recent advances in DFB lasers for ultradense WDM applications

State-of-the-art distributed feedback (DFB) laser modules integrated with a wavelength monitor are presented that provide excellent wavelength stability. By adopting unique and compact configuration, wavelength deviations of as small as a few picometers have been achieved. The laser modules are improved also in the scope of high power, high reliability, and wavelength tunability. Reliability test results of the DFB laser diodes and modules confirm a sufficiently long lifetime of more than 25 years and a small wavelength drift of less than /spl plusmn/3 pm. The developed laser modules are fully applicable to ultradense wavelength-division multiplexing applications with the current narrowest channel spacing of 25 GHz.

Low threshold current density operation of GaInAsP-InP laser with multiple reflector microcavities

We propose and demonstrate a new type of semiconductor laser having multiple reflector microcavities for the purpose of low threshold current operation. Very uniform multiple reflector microcavity structure was fabricated by electron beam (EB) lithography and selective wet chemical etching. Due to multiple reflection effect, threshold current density as low as 310 A/cm/sup 2/ (threshold current of 30 mA) was obtained at room temperature with the total cavity length of 64 /spl mu/m and the cavity width of 200 /spl mu/m.<<ETX>>

1.3 mu m InAs/sub y/P/sub 1/-/sub /y-InP strained-layer quantum-well laser diodes grown by metalorganic chemical vapor deposition

The authors have fabricated 1.3- mu m InAsP-InP separate-confinement-heterostructure (SCH) strained-layer double-quantum-well (SL-DQW) laser diodes (LDs) by metalorganic chemical vapor deposition (MOCVD). A low threshold current density of 410 A/cm/sup 2/ was obtained. The CW threshold current was as low as 1.8 mA at 20 degrees C, and maximum CW operating temperature of 120 degrees C was obtained. These characteristics are almost the same as those of well-designed GaInAsP-InP SL-QW LDs. Further improvement of the characteristics of InAsP-InP LDs is expected by optimizing the device structure. >

High Quantum Efficiency, High Output Power 1.3 µm GaInAsP Buried Graded-Index Separate-Confinement-Heterostructure Multiple Quantum Well (GRIN-SCH-MQW) Laser Diodes

We have fabricated a high quantum efficiency (40%/facet), low internal loss (5 cm-1), high output power (62 mW/facet) 1.3 µm GaInAsP buried graded-index separate-confinement-heterostructure multiple quantum well (GRIN-SCH-MQW) laser diode entirely grown by metalorganic chemical vapor deposition (MOCVD). This laser diode operated in a single longitudinal mode in a relatively wide temperature range of 35°C without any mode hopping. The minimum spectral linewidth of 2.3 MHz was realized at an output power of 7 mW for a laser diode with cavity length of 900 µm. The beam divergence angle is considerably smaller than that of the conventional DH laser diodes.

25-W 915-nm Lasers With Window Structure Fabricated by Impurity-Free Vacancy Disordering (IFVD)

We have demonstrated high-performance broad-area single-emitter lasers with window structure fabricated by newly developed impurity-free vacancy disordering (IFVD) technique. A very high pulse output power of 25 W was obtained in 100-m wide lasers without facet degradation.