Modeling the temperature performance of monolithic passively mode-locked quantum dot lasers

This paper examines and models the effect of temperature on the mode-locking stability of monolithic two-section InAs/GaAs quantum dot passively mode-locked lasers. A set of equations based on an analytic net-gain modulation phasor approach is used to model the observed mode-locking stability of these devices over temperature. The equations used rely solely on static device parameters, measured on the actual device itself, namely, the modal gain and loss characteristics and describe the hard limit where mode-locking exists. Employment of the measured gain and loss characteristics of the gain material over temperature, wavelength and current injection in the model provides a physical insight as to why the mode-locking shuts at elevated temperatures. Moreover, the model enables a temperature-dependent prediction of the range of cavity geometries (absorber to gain length ratios) where mode-locking exists. Excellent agreement between the measured and the modeled mode-locking stability over a wide temperature range is achieved for an 8-stack InAs/GaAs mode-locked laser. This is an extremely attractive tool to guide the design of monolithic passively mode-locked lasers for applications requiring broad temperature operation.