Masaki Ohya

First demonstration of novel active multi-mode interferometer (MMI) LDs integrated with 1st order-mode permitted waveguides

Here we propose novel active multi-mode-interferometer (MMI) laser diodes (LDs) for 14XXnm fiber amplifier pump applications. The waveguide of the LDs is consisted from 1x1-MMI couplers integrated with 1st order-mode permitted waveguides to enhance the total active area. Although there is no single-mode waveguide region inside the cavity, the novel active MMI-LDs emitted in stable single-transverse-mode output up to maximum output power. Moreover, they achieved high output power of 1.46W, and low driving voltage of only 1.75V at 1W output power.

High-power operation of inner-stripe GaN-based blue-violet laser diodes

We review our recent progress in novel planar blue-violet laser diodes (BV-LDs). The planar BV-LDs are characterized by an inner-stripe waveguide formed with a buried AlN current-blocking layer and a wide regrown cladding layer that also acts as a current and heat spreader. These features enable high-power operation for BV-LDs thanks to their low electrical and low thermal resistance even with a narrow-stripe waveguide. In this paper, we report successful demonstration of the planar inner-stripe BV-LDs by utilizing low-temperature-grown AlN and the regrown cladding layer. Low electrical resistance of the regrown cladding layer was confirmed by scanning spread resistance microscopy. Heat spreading characteristics were also investigated by 2-dimensional thermal simulation. The fabricated BV-LDs with a 1.4-&mgr;m-wide stripe achieved a low threshold current of 32 mA, a low threshold voltage of 4.1 V and greater than 200- mW kink-free output power under CW operation. Moreover, the kink-free output level surpassed 1,000 mW for the 1.0- &mgr;m stripe BV-LDs under 0.03%-duty-pulsed operation. The BV-LDs operated stably for more than 1,000 hours at a high output power of 200 mW at 80oC under a 50%-duty-pulsed condition. After the reliability test, transmission electron microscopy revealed no defect near the regrown interface of the tested LDs.

Low wall-plug consumption laser diodes by using active multi-mode interferometer (MMI)

We demonstrate low wall-plug consumption principle by using active multi-mode interferometer (MMI) with over 1 W output. It shows larger in the area of the active MMI contributes lower in the wall-plug consumption.

1 V and Stable Dynamic Operation of Laser Diode Using Active Multi-Mode Interferometer

A low operation voltage of only 1 V at 10 mW was achieved for 1.5 µm wavelength active multi-mode-interferometer laser diodes (MMI-LDs) due to a significant reduction in resistance of 60% compared with that of conventional LDs. We also investigated the dynamic characteristics of the MMI-LDs. Although there was concern that current modulation might cause changes in refractive index, thus, deteriorating self-imaging properties, stable 1 Gbps operation without jitter and improved roll-off frequency due to the low resistance were confirmed experimentally.

First direct observation of self-imaging effect in active multimode-interference semiconductor laser diodes

We report the first direct observation of the self-imaging effect in active multimode-interference semiconductor laser diodes (MMI-SLDs). Interference patterns inside laser diode waveguides were obtained by using the electroluminescence (EL) method. To the best of our knowledge, this result is the first direct observation of the self-imaging effect in self-photon-emitting active waveguides such as laser diodes. The observed EL pattern confirms the adequateness of the design of the higher light output-aimed MMI-SLDs.

1V operation laser diode for FTTH by using active multi-mode-interferometer (MMI)

Active multi-mode-interferometer (MMI) laser diodes (LDs) achieved low operating voltage of only 1V at 10 mW light output (/spl lambda//spl ap/1.5 /spl mu/m), due to the significant resistance reduction of 60% compared to that of regular LDs, and 1 Gbps operation.

Novel Active Multi-Mode-Interferometer (MMI) Laser Diodes Integrated with 1st Order-Mode Permitted Waveguides

We propose novel active multi-mode-interferometer laser diodes (LDs), integrated with 1storder-mode permitted waveguides. They achieved regular single-transverse-mode and high output power of 1.46W.

Cleaning of residual silicon on InP regrowth interface in MOVPE reactor

Investigating the use of tertiarybutylchloride (TBCl) to clean residual silicon from InP regrowth interfaces in an MOVPE reactor, we found the amount of the residual silicon to be greatly decreased when trimethylindium was supplied together with TBCl in order to balance the etching rate and the growth rate during the cleaning process. Using this cleaning process in the fabrication of buried hetero-structure laser diodes, we demonstrated that it improves their light-current characteristics by reducing the leakage current in the devices.

Low-current and high-reliability 80/spl deg/C operation 650 nm-5 mW-LDs for DVD

Low-current and high-reliability 80 C operation 650 nm 5 mW GaInP MQW laser diodes have been developed. The LDs are very attractive for use as light sources in advanced optical digital versatile disc applications.