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

Abstract

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 Type Membrane DFB Laser With Surface Grating

“…In addition to the improvements of internal quantum efficiency and waveguide loss, introduction of a thinner core layer (∼ 200 nm) and shorter cavity structure (∼ 50 µm) is required toward realization of ultra-low threshold current operation shown in Fig.3 The differential series resistance and the voltage at the threshold were around 78 and 1.7 V, respectively. Since the rise-up voltage was around 0.8 V and was similar to conventional lasers in 1.5 µm wavelength region, the relatively high threshold voltage is attributed to a higher series resistance which was 3.1 times higher than that of LCI-DFB laser with 400 nm thick core layer prepared on a SI-InP substrate [16]. A continuous-wave operation was not obtained because of heat generation due to the high series resistance.…”

“…In this letter, we introduced surface grating structure [16], [17] and demonstrated much lower threshold current operation of the LCI membrane laser. Figure 1 shows a schematic structure of the fabricated LCImembrane-DFB laser with a surface grating structure, where the total core layer thickness was about 450 nm, and the top and bottom cladding layers were composed of air (n = 1) and SiO 2 (n = 1.45), respectively.…”

“…Therefore, internal quantum efficiency η i of the fabricated LCI-membrane laser is thought to be less than 10%, and the threshold current is expected to be 9.2 mA. In order to suppress such non-radiative recombination, we already reported some novel core structures suited for LCI-membrane lasers and can expect their highly-efficient operations with η i of around 70% [16], [17]. Furthermore, poor lasing characteristics are attributed to poor a BCB bonding process since air voids were trapped in the bonding interface which might have resulted in large waveguide loss.…”

50-Gbit/s operation of lateral pin diode structure electro-absorption modulator integrated DFB laser

“…Several InP-based LCI lasers have reported [1][2][3][4] . Recently, we have used thermal diffusion and ion implantation to realize lateralcurrent-injection photonic crystal lasers 5 and a DFB laser 6 .…”

Lateral current injection laser with uniformly distributed quantum-well structure

“…As a step to realize an injection-type membrane laser, we introduced a latera-current-injection (LCI) structure [5] and demonstrated LCI-Fabry-Perot (FP) lasers [6] and DFB lasers [7] consisting of compressively-strained (CS) 5 QWs with a 400-nm-thick GaInAsP core layer prepared on a semi-insulating (SI) InP substrate. However, relatively low internal quantum efficiency of around 40 % [8], which may be attributed to large carrier leakage from n-InP to p-InP through optical confinement layers (OCLs), was an issue to be solved.…”