Room-temperature continuous-wave operation of membrane distributed-reflector laser

Abstract

In this paper, we report on the first ever demonstration of a continuous-wave operation of an injection-type membrane distributed-reflector (DR) laser at room temperature. A threshold current of 250 µA was obtained with a stripe width of 0.7 µm, a DFB region length of 30 µm, and a DBR region length of 90 µm. An external differential quantum efficiency of 11% with a light output ratio between the front and the rear of 6.7 was obtained at the front waveguide.

High-Efficiency Operation of Membrane Distributed-Reflector Lasers on Silicon Substrate

“…This device has no front waveguide, which means the device is cleaved at the active DFB section. The η df value is around 2.5 times higher than that reported in our previous work [48]. These improvements are considered to be caused by better matching between the DFB mode and the Bragg wavelength of the DBR section.…”

“…We set the DFB period to match the shorter wavelength side mode of the stop band of the DFB section to the center wavelength (the Bragg wavelength) of the DBR section. The reflectivity of the DBR was designed to be higher than 95% for the DBR section longer than 90 μm [48]. In this calculation, the waveguide loss of the passive section was assumed to be 12 cm −1 including the material absorption loss.…”

“…Next, the fabrication process is briefly explained. The initial wafer structure was almost the same as that used in previous work [48]. The difference was the doping concentration of the p-InP upper cladding layer which was reduced to 5 × 10 17 cm −3 in order to reduce the waveguide loss, and p + -GaInAs (100 nm) and p + -GaInAsP (20 nm) were used for better contact resistance.…”

“…However, these devices have poor light output characteristics. The DR structure, which improves the light output efficiency [44]- [47], was introduced, and an asymmetric light output characteristic with the ratio from the front to the rear sides of 6.7 was achieved [48]. Energy cost analysis of the membrane DR lasers was also carried out, and a suitable cavity structure was pro- posed in terms of the energy cost [49].…”

Integrated Optical Link on Si Substrate Using Membrane Distributed-Feedback Laser and p-i-n Photodiode

“…We adopted a BJB structure to integrate the membrane DFB laser with a passive waveguide section [48]; a low threshold current of 0.23 mA was achieved with the BJB waveguide [49]. Integration with a distributed-Bragg reflector enhanced the output efficiency [50]. Recent works showed the high speed modulation properties of membrane DFB lasers at low-bias currents [51], [52].…”