Ryo Osabe

GaInAsP/InP lateral-current-injection distributed feedback laser with a-Si surface grating.

We fabricated a novel lateral-current-injection-type distributed feedback (DFB) laser with amorphous-Si (a-Si) surface grating as a step to realize membrane lasers. This laser consists of a thin GaInAsP core layer grown on a semi-insulating InP substrate and a 30-nm-thick a-Si surface layer for DFB grating. Under a room-temperature continuous-wave condition, a low threshold current of 7.0 mA and high efficiency of 43% from the front facet were obtained for a 2.0-μm stripe width and 300-μm cavity length. A small-signal modulation bandwidth of 4.8 GHz was obtained at a bias current of 30 mA.

Lateral-Current-Injection Distributed Feedback Laser With Surface Grating Structure

As a step toward the realization of injection-type membrane distributed feedback (DFB) lasers, which are expected to be important components of optical interconnections, we realized lateral-current-injection DFB (LCI-DFB) lasers with surface grating structures prepared on semiinsulating InP substrates. First, we designed the surface grating structure to have a high index-coupling coefficient together with a high optical confinement in the quantum wells. Then, we investigated the surface grating structure formed on an amorphous-Si (a-Si) layer deposited on the GaInAsP/InP initial wafer containing five quantum wells. A moderately low threshold current of 7.0 mA and a high differential quantum efficiency of 43% from the front facet were obtained under a continuous-wave operating condition at room temperature for a uniform grating LCI-DFB laser with a stripe width of 2.0 μm and a cavity length of 300 μm. A threshold current of 5.8 mA was obtained with a λ/4 phase-shifted LCI-DFB laser with a-Si surface grating. Furthermore, a small-signal modulation bandwidth of 4.8 GHz was obtained at a bias current of 30 mA with a modulation current efficiency factor of 1.0 GHz/mA1/2.

Low Threshold Current Density Operation of a GaInAsP/Si Hybrid Laser Prepared by Low-Temperature N2 Plasma Activated Bonding

The integration of III–V active devices on a Si platform utilizing direct bonding is an attractive way to realize large-scale photonic integrated circuits. Because plasma activated bonding (PAB) is expected to have a higher bonding strength at a lower heating temperature as compared to conventional bonding methods, PAB is attractive for the reduction of non-radiative recombination centers in the III–V active region caused by thermal expansion during the bonding process. A GaInAsP/Si hybrid laser was fabricated with low-temperature (150 °C) N2 PAB, and a low threshold current density of 850 A/cm2 (170 A/cm2 per quantum well) was obtained.

Lateral-Current-Injection Type Membrane DFB Laser With Surface Grating

Toward the light source for on-chip interconnection, a current-injection-type membrane distributed feedback laser with a surface gating structure is demonstrated. In this device, 450-nm-thick GaInAsP/InP layers with lateral-current-injection structure prepared by a two step OMVPE regrowth-method is bonded on a host substrate by using Benzocyclobutene bonding process. A threshold current of Ith=11 mA is obtained with a cavity length of 300 μm and a stripe of 1 μm.

Bonding and Photoluminescence Characteristics of GaInAsP/InP Membrane Structure on Silicon-on-Insulator Waveguides by Surface Activated Bonding

Surface activated bonding (SAB) technology was investigated to realize InP-based active photonic devices on a silicon-on-insulator (SOI) substrate for highly compact photonic integrated circuits (PICs). A wide area five-quantum-wells (5QWs) GaInAsP/InP membrane structure was successfully bonded onto an SOI waveguide using a low-temperature (150 °C) N2 plasma SAB method. The full width at half maximum (FWHM) of the photoluminescence (PL) of the 5QWs membrane structure on SOI was comparable to that of conventional QWs. It was revealed that the PL intensity distribution and peak wavelength shift of the GaInAsP 5QWs structure around the Si waveguides were small.

Investigation of bonding strength and photoluminescence properties of InP/Si surface activated bonding

A low-temperature direct wafer bonding technique has been researched by using plasma treatment. Si-to-Si direct bonding strength was 1.6 MPa by using plasma pretreatment prior to the heating and weighting. 1.4 MPa of InP/Si bonding strength was obtained by improving chemical cleaning process. On the other hand, photoluminescence properties of GaInAs/InP quantum wells bonded on Si substrate were investigated. An introduction of a 30-nm-thick superlattice buffer on the top of the wafer greatly suppressed photoluminescence intensity degradation near the bonded interface.

AlInAs selective oxidation for GaInAsP/Si hybrid semiconductor laser using surface activated bonding

Toward a GaInAsP/Si hybrid laser with an AlInAs oxidation current confinement structure, AlInAs oxidation on a III-V/Si by Surface Activated Bonding was demonstrated.

Lateral current injection laser with uniformly distributed quantum-well structure

Uniformly distributed quantum-well structure was introduced to a lateral-current-injection (LCI) laser to realize high internal quantum efficiency operation. As the result, superior light output characteristic was obtained with the internal quantum efficiencies of 70%.

Design of multi-functional GaInAsP/Si hybrid semiconductor optical amplifier array with AlInAs-oxide current confinement layer

Novel configuration of multi-functional SOA array by III-V/Si hybrid technique using one-time III-V/Si wafer bonding is proposed. A III-V/Si hybrid structure can realize multi-functional SOA array with different gain characteristics by tuning Si waveguide width.

Lateral current injection type GaInAsP/InP DFB laser with a-Si surface grating

Lateral current injection DFB laser with a-Si surface grating was demonstrated, as step to realize membrane laser. The threshold current of 7.0 mA and the differential quantum efficiency of 43% from the front facet were obtained.