Hirohiko Kobayashi

Tapered thickness MQW waveguide BH MQW lasers

We propose and demonstrate a novel 1.3 /spl mu/m InGaAsP/InGaAsP multiple-quantum-well (MQW) BH Fabry-Perot laser diode monolithically integrated with a MQW tapered thickness waveguide. A selective area growth (SAG) technique is used to fabricate the tapered thickness waveguide with low absorption loss and to integrate it with the MQW gain region with a high coupling efficiency. We achieve very narrow vertical and lateral far-field FWHM of 11.8/spl deg/ and 8.0/spl deg/, with low threshold current of 19 mA and high slope efficiency of 0.25 mW/mA.<<ETX>>

Narrow-beam divergence 1.3-/spl mu/m multiple-quantum-well laser diodes with monolithically integrated tapered thickness waveguide

This paper describes the optimum design, fabrication, and performance of a 1.3-/spl mu/m multiple-quantum-well (MQW) laser diode monolithically integrated with a tapered thickness spot-size transformer. The dependence of the lasing characteristics on the thickness distribution of the core layer and on the current injection profile of the device were analyzed. This integrated laser with its optimized structure performed at a low threshold current of 22.2 mA, even at 85/spl deg/C. The integrated spot-size transformer effectively reduced the lateral and vertical far-field FWHMs to 8/spl deg/ and 9/spl deg/, respectively. A very long lifetime of over 1/spl times/10/sup 5/ h was estimated at 85/spl deg/C and 8 mW under CW operation.

Optimum asymmetric mirror facet structure for high-efficiency semiconductor lasers

A design theory for asymmetric mirror facet structure lasers that takes into account the spatial hole burning (SHB) effect along the cavity is presented. It is shown that the SHB effect reduces the external quantum efficiency in asymmetric mirror facet structure lasers, and the front facet reflectivity has an optimum value depending on the internal loss for high-efficiency operation. A slope efficiency of more than 50% has been obtained in lasers based on the new design theory. It is noted that nonuniform current injection is one of the most useful methods for increasing the external quantum efficiency, which is reduced by the SHB effect. >

Low driving voltage InP-based Mach-Zehnder modulators for compact 128 Gb/s DP-QPSK module

We demonstrated the InP-based DP-QPSK modulator monolithically integrated with four Mach-Zehnder modulators planarized by the benzocyclobutene polymer. Clear eye-opening under 32 Gb/s operation was successfully achieved in all of four Mach-Zehnder modulators at a low driving voltage of 1.8 Vpp.

Tapered thickness waveguide InGaAsP/InP BH MQW lasers

Optical alignment in laser modules represents major cost barriers for subscriber systems. From the point of high volume production and low cost views, integration of the laser and the spot-size transformer is desirable. Recently we have demonstrated a narrow beam divergence tapered thickness MQW spot-size transformer integrated Fabry-Perot BH InGaAsP MQW lasers using a selective area growth technique. Our tapered thickness waveguide MQW spot-size transformer is fully compatible for the laser fabrication process so that an increase in the fabrication cost will be minimized. Here we introduce our structure and lasing performance.

Optical feedback effect to modulation characteristics of tapered thickness waveguide BH MQW lasers under low-bias, high-temperature condition

Summary form only given. In conclusion, we have demonstrated low-bias, high-temperature modulation of tapered thickness waveguide BH InP MQW lasers with an external optical feedback. A penalty-free transmission over 40 km was confirmed with -14-dB feedback at 85 C. We confirmed that our lasers have a potential for low cost subscriber systems.

1.3 /spl mu/m InGaAsP/InP strained-layer MQW lasers fabricated by reactive ion etching and MOVPE regrowth with CH/sub 3/Cl addition

Using reactive ion etching and MOVPE regrowth with CH/sub 3/Cl addition, 1.3 /spl mu/m InGaAsP-InP BH lasers with excellent high temperature characteristics and uniformity were fabricated. A narrow-beam-divergence laser with tapered stripe width is also demonstrated.

Zero-bias-voltage modulation of narrow-beam-divergence tapered-thickness waveguide lasers with semi-insulating blocking layer

We demonstrated zero-bias-voltage modulation of narrow-beam-divergence laser diodes by the reduction of the parasitic capacitance using semi-insulating blocking layer. A laser with low threshold current of 10.5 mA enabled 622 Mbit/s modulation under zero-bias-voltage condition even at 85/spl deg/C.