1.3-μm InAsP modulation-doped MQW lasers

The effect of both n-type and p-type modulation doping on multipie-quantum-well (MQW) laser performances was studied using gas-source molecular beam epitaxy (MBE) with the object of the further improvement of long-wavelength strained MQW lasers, The obtained threshold current density was as low as 250 A/cm(2) for 1200-mu m-long devices in n-type modulation-doped MQW (MD-MQW) lasers, A very tow CW threshold current of 0.9 mA was obtained in 1.3-mu m InAsP n-type MD-MQW lasers at room temperature, which is the lowest ever reported for long-wavelength lasers using n-type modulation doping, and the lowest value for lasers grown by all kinds of MBE in the long-wavelength region, Both a reduction of the threshold current and the carrier lifetime in n-type MD MQW lasers caused the reduction of the turn-on delay time by about 30%. The 1.3-mu m InAsP strained MQW lasers using n-type modulation doping with very Low power consumption and small turn-on delay time are very attractive for laser array applications in high-density parallel optical interconnection systems. On the other hand, the differential gain was confirmed to increase by a factor of 1.34 for p-type MD MQW lasers (N-A = 6 x 10(18) cm(-3)) as compared with undoped MQW lasers, and the turn-on delay time was reduced by about 20% as compared with undoped MQW lasers, These results indicate that p-type modulation doping is suitable for high-speed lasers.