Hung-Pin D. Yang

1.3-/spl mu/m InAs-InGaAs quantum-dot vertical-cavity surface-emitting laser with fully doped DBRs grown by MBE

We report InAs-InGaAs quantum-dot vertical-cavity surface-emitting lasers (VCSELs) grown by molecular beam epitaxy with fully doped n- and p-doped AlGaAs distributed Bragg reflectors and including an AlAs layer to form a current and waveguiding aperture. The metal contacts are deposited on a topmost p/sup +/-GaAs contact layer and on the bottom surface of the n/sup +/-GaAs substrate. This conventional selectively oxidized top-emitting device configuration avoids the added complexity of fabricating intracavity or coplanar ohmic contacts. The VCSELs operate continuous-wave at room temperature with peak output powers of 0.33 mW and differential slope efficiencies up to 0.23 W/A. The peak lasing wavelengths are near 1.275 /spl mu/m, with a sidemode suppression ratio of 28 dB.

Characteristics of InGaAs Submonolayer Quantum-Dot and InAs Quantum-Dot Photonic-Crystal Vertical-Cavity Surface-Emitting Lasers

We have made InGaAs submonolayer (SML) quantum-dot (QD) and InAs QD photonic-crystal vertical-cavity surface-emitting lasers (PhC-VCSELs) for fiber-optic communications in the 990 and 1300 nm ranges, respectively. The active region of the InGaAs SML QD PhC-VCSEL contains three InGaAs SML QD layers, with each of the SML QD layer formed by alternating depositions of InAs and GaAs. The active region of the InAs QD PhC-VCSEL contains 17 undoped InAs-InGaAs QD layers. Both types of QD PhC-VCSELs exhibit single-mode characteristics throughout the current range, with side-mode suppression ratio (SMSR) larger than 35 dB. A maximum output power of 5.7 mW has been achieved for the InGaAs SML QD PhC-VCSEL. The near-field image study of the QD PhC-VCSELs indicates that the laser beam is well confined by the photonic-crystal structure of the device.

Single-mode InGaAs submonolayer quantum dot photonic crystal VCSELs

An InGaAs submonolayer (SML) quantum dot photonic crystal vertical-cavity surface-emitting laser (QD PhC-VCSEL) for fibre-optic applications is demonstrated for the first time. The active region of the device contains three InGaAs SML QD layers. Each of the InGaAs SML QD layers is formed by alternate deposition of InAs (<1 ML) and GaAs. Single-fundamental-mode CW output power of 3.8 mW at 28 mA has been achieved in the 990 nm range, with a threshold current of 0.9 mA. A side-mode suppression ratio (SMSR) larger than 35 dB has been observed over the entire current operating range.

High-Power Single-Mode Vertical-Cavity Surface-Emitting Lasers with Multi-Leaf Holey Structure

A single-mode oxide-confined vertical-cavity surface-emitting laser (VCSEL) with multi-leaf holey structure for fiber-optic applications is demonstrated. Single fundamental mode continuous-wave output power of over 3 mW has been achieved in the 850 nm range, with a threshold current of approximately 0.5 mA. Side-mode suppression ratio (SMSR) larger than 22 dB has been measured.

High-power broad-area InGaNAs/GaAs quantum-well lasers in the 1200 nm range

Broad-area InGaNAs/GaAs quantum-well (QW) edge-emitting lasers on GaAs substrates in the 1200 nm range are reported. The epitaxial layers of the InGaNAs/GaAs QW laser wafers were grown on n⁺-GaAs substrates by using metal-organic chemical vapor deposition (MOCVD). The thickness of the InGaNAs/GaAs QW layers is 70 Å/1200 Å. The indium content (x) of the In<inf>x</inf>Ga<inf>1−x</inf>N<inf>y</inf>As<inf>1−y</inf> QW layers is estimated to be 0.35 to 0.36, while the nitrogen content (y) is estimated to be 0.006 to 0.008. More indium content (In) and nitrogen content (N) in the InGaNAs QW layer enables the laser emission up to 1300 nm range. The epitaxial layer quality, however, is limited by the strain in the grown layer. The devices were made with different ridge widths from 5 to 50 µm. A very low threshold current density (J<inf>th</inf>) of 80 A/cm² has been obtained for the 50µm×500µm LD. A number of InGaNAs/GaAs epi-wafers were made into broad-area LDs. A maximum output power of 95 mW was measured for the broad-area InGaNAs/GaAs QW LDs. The variations in the output powers of the broad-area LDs are mainly due to strain the InGaNAs QW layers.

Photonic-crystal light-emitting diodes on p-type GaAs substrates for optical communications

Oxide-confined photonic-crystal (PhC) light-emitting diodes (LEDs) on p-type GaAs substrate in the 830 nm range are reported. The device consists of a bottom distributed Bragg reflector (DBR), quantum wells (QWs), and a top DBR, with a photonic-crystal structure formed within the n-type ohmic contact ring for light extraction. The etching depth of the PhC holes is 17-pair out of the 22-pair top DBR being etched off. The internally reflected spontaneous light emission can be extracted out of PhC holes because of lower reflectance within those areas. High-resolution micrographic imaging studies indicate that the device emits light mainly through the photonic-crystal holes and it is suitable for optical communications.

Single-Mode Vertical-Cavity Surface-Emitting Lasers with a Deep-Etched Half-Ring-Shaped Holey Structure

A single-mode oxide-confined vertical-cavity surface-emitting laser (VCSEL) with deeply-etched half-ring-shaped holey structure for fiber-optic applications is demonstrated. Single fundamental mode continuous-wave output power of 2.6 mW has been achieved in the 850 nm range, with a threshold current of approximately 1 mA. Side-mode suppression ratio (SMSR) larger than 26 dB has been measured. Contrary to the previously reported surface relief methods, the deep-etched (approximately 2.2 µm in depth) holey structure in this paper provides another approach to achieve single-mode operation of the VCSEL with a larger oxide aperture.

Single-mode InGaAs photonic crystal vertical-cavity surface-emitting lasers emitting at 1170 nm

We have made MOCVD-grown InGaAs photonic crystal vertical-cavity surface-emitting lasers (PhC-VCSELs) for fiber-optic applications. Multi-mode InGaAs VCSELs have achieved a maximum power of over 1 mW. Single-mode characteristics of 0.18 mW of the PhC-VCSELs have been made by using the combined AlOx oxide layer with proton-implantion for better current confinement.

Characteristics of Cross-Shaped Polarization-Switching Vertical-Cavity Surface-Emitting Lasers for Dual-Channel Communications

The polarization switching of a cross-shaped vertical-cavity surface-emitting laser (VCSEL) for dual-channel communications is demonstrated. The polarization of the lasing output is controlled by the asymmetry in geometry of the device and direction of current injection. High output power ratio of over 5, between two orthogonal (perpendicular) polarization directions has been achieved. The lasing output of the device can be switched between two nearly orthogonal directions.

Characteristics of Single-Mode InGaAs Submonolayer Quantum-Dot Photonic-Crystal Vertical-Cavity Surface-Emitting Lasers

An InGaAs submonolayer (SML) quantum-dot photonic-crystal vertical-cavity surface-emitting laser (QD PhC-VCSEL) for fiber-optic applications is demonstrated for the first time. The active region of the device contains three InGaAs SML QD layers. Each of the InGaAs SML QD layers is formed by alternate depositions of InAs (<1 ML) and GaAs. A single-fundamental-mode CW output power of 3.8 mW at 28 mA has been achieved in the 990 nm range, with a threshold current of 0.9 mA. A side-mode suppression ratio (SMSR) larger than 35 dB has been demonstrated over the entire current operation range. The beam profile and near-field image study of the PhC-VCSEL indicates that the laser beam is well confined by the photonic crystal structure of the device.