Radiative efficiency of MOCVD grown QD lasers

The optical spectral gain characteristics and overall radiative efficiency of MOCVD grown InGaAs quantum dot lasers have been evaluated. Single-pass, multi-segmented amplified spontaneous emission measurements are used to obtain the gain, absorption, and spontaneous emission spectra in real units. Integration of the calibrated spontaneous emission spectra then allows for determining the overall radiative efficiency, which gives important insights into the role which nonradiative recombination plays in the active region under study. We use single pass, multi-segmented edge-emitting in which electrically isolated segments allow to vary the length of a pumped region. In this study we used 8 section devices (the size of a segment is 50x300 μm) with only the first 5 segments used for varying the pump length. The remaining unpumped segments and scribed back facet minimize round trip feedback. Measured gain spectra for different pump currents allow for extraction of the peak gain vs. current density, which is fitted to a logarithmic dependence and directly compared to conventional cavity length analysis, (CLA). The extracted spontaneous emission spectrum is calibrated and integrated over all frequencies and modes to obtain total spontaneous radiation current density and radiative efficiency, ηr. We find ηr values of approximately 17% at RT for 5 stack QD active regions. By contrast, high performance InGaAs QW lasers exhibit ηr ~50% at RT.

[1]  Dennis G. Deppe,et al.  Quantum dot laser diode with low threshold and low internal loss , 2009 .

[2]  Diana L. Huffaker,et al.  Strain compensation technique in self-assembled InAs/GaAs quantum dots for applications to photonic devices , 2009 .

[3]  Meimei Z. Tidrow,et al.  High detectivity InGaAs/InGaP quantum-dot infrared photodetectors grown by low pressure metalorganic chemical vapor deposition , 2004 .

[4]  David T. D. Childs,et al.  Analysis of 1.2μm InGaAs∕GaAs quantum dot laser for high power applications , 2009 .

[5]  Serge Luryi,et al.  Tunneling-injection quantum-dot laser: ultrahigh temperature stability , 2001 .

[6]  Chennupati Jagadish,et al.  InGaAs quantum dots grown with GaP strain compensation layers , 2004 .

[7]  Pallab Bhattacharya,et al.  Long wavelength quantum-dot lasers selectively populated using tunnel injection , 2007 .

[8]  Tao Yang,et al.  Temperature Sensitivity Dependence on Cavity Length in p-Type Doped and Undoped 1.3-$\mu$ m InAs–GaAs Quantum-Dot Lasers , 2008, IEEE Photonics Technology Letters.

[9]  Manoj Kanskar,et al.  Characteristics of InGaAs quantum dots grown on tensile-strained GaAs1−xPx , 2005 .

[10]  Peter Blood,et al.  Characterization of semiconductor laser gain media by the segmented contact method , 2003 .

[11]  S. Sanguinetti,et al.  Efficient room temperature carrier trapping in quantum dots by tailoring the wetting layer , 2003 .

[12]  M. Hopkinson,et al.  Origin of Temperature-Dependent Threshold Current in p-Doped and Undoped In(Ga)As Quantum Dot Lasers , 2008, IEEE Journal of Selected Topics in Quantum Electronics.

[13]  M. Kanskar,et al.  Spontaneous Radiative Efficiency and Gain Characteristics of Strained-Layer InGaAs–GaAs Quantum-Well Lasers , 2008, IEEE Journal of Quantum Electronics.

[14]  Nelson Tansu,et al.  Current injection efficiency of InGaAsN quantum-well lasers , 2005 .

[15]  Kristian M. Groom,et al.  Low threshold current density and negative characteristic temperature 1.3 μm InAs self-assembled quantum dot lasers , 2007 .

[16]  M. Kanskar,et al.  Temperature sensitivity of InGaAs quantum-dot lasers grown by MOCVD , 2006, IEEE Photonics Technology Letters.

[17]  M. Hopkinson,et al.  Nonradiative Recombination in Multiple Layer In(Ga)As Quantum-Dot Lasers , 2007, IEEE Journal of Quantum Electronics.

[18]  Sam Kyu Noh,et al.  Effects of high potential barrier on InAs quantum dots and wetting layer , 2002 .

[19]  Jasprit Singh,et al.  Self-assembled quantum dots: A study of strain energy and intersubband transitions , 2002 .

[20]  Diana L. Huffaker,et al.  Ground-state lasing of stacked InAs∕GaAs quantum dots with GaP strain-compensation layers grown by metal organic chemical vapor deposition , 2006 .