Yumi Yamada

High-power InGaAs/AlGaAs laser diodes with decoupled confinement heterostructure

High power InGaAs/AlGaAs laser diodes with decoupled confinement heterostructure (DCH) have been developed. Almost Al-free waveguide and cladding layers were realized in 980 nm DCH laser diodes without degrading temperature characteristics. The extremely low electrical and thermal resistances allowed high power and efficient operation. The maximum CW output power as high as 9.5 W was obtained with 100-micrometer-aperture broad area. DCH laser diode. The maximum efficiency was 55% at 2.5 W. The series resistance of 1.8-mm long cavity was 0.04(Omega) and internal loss was 1.5 cm-1. The characteristic temperature (T0) was 155 K. The substantially Al-free DCH structure enables easy fabrication of various index guided laser diodes. We have developed two types of real index guided laser diodes, buried- ridge and self-aligned structure. Buried-ridge laser diode presented 1.3 W maximum CW output power and 500 mW single mode operation. Self-aligned structure laser diodes showed 1.4 W CW output power and 700 mW single mode operation with better reproducibility.

Characteristics and reliability of high-power InGaAs/AlGaAs laser diodes with decoupled confinement heterostructure

In order to overcome catastrophic optical damage, decoupled confinement heterostructure (DCH) featuring a broadened waveguide and thin carrier block layers have been developed. Due to decoupling of carrier and optical confinement, a DCH laser can be designed more flexibly than a conventional separated confinement heterostructure laser, i.e., laser diodes can be designed with a variety of gain coupling factor (Gamma) (perpendicular), quantum-well number NW, keeping the beam divergence angle constant.

High-power and highly reliable 980-nm lasers with window structure using impurity-free vacancy disordering

High power and reliable 980nm single mode lasers are required for pumping EDFAs and 915, 940, 975nm broad area lasers are demanded for pumping double clad fiber lasers and amplifiers. While we have demonstrated high power lasers by using decoupled confinement heterostructure (DCH) , we employed a window structure due to impurity free vacancy disordering (IFVD.) 980nm single mode lasers showed complete rollover with I=4A(CW). For 12000 hour lifetest at 700mW-40C, no sudden failure was observed. And the average gradual degradation rate was zero. Also the window structure applied to 975nm broad area laser successfully. The degradation rate during 500 hours operation was decreased to zero.

915nm high-power broad area laser diodes with ultra-small optical confinement based on Asymmetric Decoupled Confinement Heterostructure (ADCH)

915nm high-power and high-reliability single emitter laser diodes based on Asymmetric Decoupled Confinement Heterostructure (ADCH) are demonstrated. Advantage of ADCH is that it can optimize active layer confinement () and confinement ratio of p- to n-doped layer (p/n), independently, to manage large effective spot size and low internal loss without any penalty in carrier confinement. 4mm-cavity, 100m wide stripe LDs with large effective spot size of 1.5m demonstrates record high Catastrophic-optical-damage (COD) free operation over 42W output. Accelerated aging tests are conducted for 325 devices in total with 1.8 million device hours. Mean time to failure of random failure mode is estimated to be 1.1 million hours for 12W at room temperature.

High power 980nm pump laser diodes with decoupled confinement hetero-structure

700mW fiber-output was attained from a narrow-stripe InGaAs/AlGaAs decoupled confinement hetero-structure laser. The failure rate at 300mW-25deg.C was estimated to be 430FIT with 90% confidence level from the accelerated aging test of 1.4million device-hours.

High polarization purity operation of 99% in 9xx-nm broad stripe laser diodes

Polarization characteristics of self-aligned stripe (SAS) laser diodes (LDs) and Ridge-LDs are investigated to realize highly efficient polarization beam combined (PBC) LD modules. Vertical layers of both lasers are designed identically. Near field patterns (NFP) of TM polarization for the Ridge-LD showed peaks at the side edges, as expected by the strain simulation. On the other hand, SAS-LD showed a relatively flat and weak profile. Polarization purity (ITE/ (ITE+ITM)) of SAS-LDs exceeds 99%, while those of the Ridge-LDs are as low as 96%. It is confirmed that our SAS-LDs are suitable sources for PBC with low power loss.

Ultimate high power operation of 9xx-nm single emitter broad stripe laser diodes

Design optimization of single emitter broad stripe 9xx-nm laser diodes was studied to achieve ultimate high power and high efficiency operation for a use in fiber laser pumping and other industrial applications. We tuned laser vertical layer design and stripe width in terms of optical confinement as well as electrical resistance. As a result, newly designed LDs with 4mm-long cavity and 220 μm-wide stripe successfully demonstrate maximum CW output power as high as 33 W and high efficiency operation of more than 60 % PCE even at 27 W output power. In pulse measurement, the maximum output of 68 W was obtained.

High power and widely tunable external cavity diode laser with a single-angled-facet laser chip

High power external cavity diode lasers were developed in the wavelength region of 1µm by using single-angled facet laser diodes. 330mW output and 130nm tuning were achieved in the conventional Littman-Metcalf configuration.

Potential of DCH structure for higher brightness laser diode

Summary form only given. We have proposed the DCH structure for high power LDs. DCH, which stands for Decoupled Confinement Heterostructure, features a broadened waveguide and carrier blocking layer. The broad waveguide results in low Gamma and an ideal Gaussian shape optical mode. Providing carrier blocking layers makes it possible to freely design the optical guide system independently of the carrier confinement. The brightness that was achieved in the GaAs/AlGaAs LD was about twice as high as the market standard level. In this paper we introduce the potential of the InGaAs/AlGaAs-DCH structure for higher brightness LDs. Our concept is to realize the high brightness LD by using AlGaAs to obtain a high quality crystal and at the same time we adopt the DCH structure to reduce the resistance. This concept performs most effectively on InGaAs/AlGaAs LD from the perspective of material characteristics.

High power operation of DFB laser diodes with a decoupled confinement heterostructure

Summary form only given. As a suitable epitaxial structure for high power and high brightness LDs, we have proposed a decoupled confinement heterostructure (DCH) and reported on the characteristics of the devices. Here we present the results from a grating integrated structure, narrow-stripe DFB LD, based on DCH technology, and reveal the potential for single longitudinal and single spatial mode operation.