Directly modulated 13 μm quantum dot lasers epitaxially grown on silicon

Abstract

We report the first demonstration of direct modulation of InAs/GaAs quantum dot (QD) lasers grown on on-axis (001) Si substrate. A low threading dislocation density GaAs buffer layer enables us to grow a high quality 5-layered QD active region on on-axis Si substrate. The active layer has p-modulation doped GaAs barrier layers with a hole concentration of 5 × 10 cmto suppress gain saturation. Small-signal measurement on a 3 × 580 μm Fabry-Perot laser showed a 3dB bandwidth of 6.5 GHz at a bias current of 116 mA. A 12.5 Gbit/s non-return-to-zero signal modulation was achieved by directly probing the chip. Open eyes with an extinction ration of 3.3dB was observed at room temperature. The bit-error-rate (BER) curve showed no error-floor up to BER of 1 × 10. 12 km single-mode fiber transmission experiments using the QD laser on Si showed a low power penalty of 1 dB at 5Gbit/s. These results demonstrate the potential for QD lasers epitaxially grown on Si to be used as a low-cost light source for optical communication systems.

Effects of modulation p doping in InAs quantum dot lasers on silicon

“…14,15 The impact of p doping on the laser modulation response has been predicted and verified. [16][17][18] p doping has also been proved to facilitate ground-state (GS) lasing in short-cavity lasers due to improvement in the GS gain and hole-to-electron capture rate ratio. 15,19 However, the effect of p doping on the gain performance in the QD active region has not been studied by a first-principles gain model.…”

Directly Modulated Single‐Mode Tunable Quantum Dot Lasers at 1.3 µm

“…It is worth mentioning that InAs/GaAs QD lasers typically have direct modulation bandwidths around 10 GHz due to strong gain compression and low saturated gain. [39][40][41][42][43] Currently, the frequency response bandwidth of the device was limited by the relatively long cavity length and the large pad capacitance of the electrodes, which are not optimized for high-frequency operation. To further improve the bandwidth, the pad capacitance can be reduced by depositing the metals on a several micron-thick benzocyclobutene (BCB, = 2.6) layer.…”

Dynamics of Quantum Dot Lasers on Silicon

“…However, to use direct modulation, a response much faster than 25 Gb/s is required. Whereas 25 Gb/s PAM-4 modulation of a QD laser on Si has been realised [1], the so far fastest reported small-signal bandwidth is only 6.5 GHz [2]. Yet as the 10 Gb/s Ethernet Passive Optical Network becomes the leading technology for fiber-to-the-home access, there is a large market emerging for inexpensive lower modulation bandwidth lasers.…”