Analysis of hybrid mode-locking of two-section quantum dot lasers operating at 1.5 micron

For the first time a detailed study of hybrid mode-locking in two- section InAs/InP quantum dot Fabry-Pérot-type lasers is presented. The output pulses have a typical upchirp of approximately 8 ps/nm, leading to very elongated pulses. The mechanism leading to this typical pulse shape and the phase noise is investigated by detailed radio-frequency and optical spectral studies as well as time-domain studies. The pulse shaping mechanism in these lasers is found to be fundamentally different than the mechanism observed in conventional mode-locked laser diodes, based on quantum well gain or bulk material. ©2009 Optical Society of America

Gain measurements of Fabry-Perot InP/InGaAsP lasers using an ultra high resolution spectrometer

In this paper we present the use of an ultra-high resolution (20 MHz) spectrometer to measure the gain in a Fabry-Pérot InGaAsP laser from subthreshold ASE spectra. The method is derived from the Hakki-Paoli method. A non-linear least-squares fitting of the observed modes is used to extract the gain from the line shape. Each mode of the measured spectrum is fully resolved and fitted separately. Thus the spectral gain curve is not restricted to a parabolic function. The optical gain spectrum and the differential gain are determined. These parameters will be used in our laser simulations

Observation of Q-switching and mode-locking in two-section InAs/InP (100) quantum dod lasers around 1.55 μm

For the first time passive mode-locking in two-section quantum-dot lasers operating at wavelengths around 1.55 µm is reported. Pulse generation at 4.6 GHz from a 9-mm long device is verified by background-free autocorrelation, RF-spectra and real-time oscilloscope traces. The output pulses have a 7 nm optical bandwidth and are stretched in time and heavily up-chirped with a value of 20 ps/nm. From a 7 mm long device Q-switching is observed over a large operating regime. The lasers have been realized using a fabrication technology that is compatible with further photonic integration, and can perform the function of e.g. a mode-comb generator

Design, fabrication and characterization of an InP-based tunable integrated optical pulse shaper

A tunable integrated semiconductor optical pulse shaper is presented. The device consists of a pair of 200 GHz arrayed waveguide gratings with an array of electrooptical phase modulators in between. It has been fabricated in InP/InGaAsP material for operation at wavelengths around 1.55 µm, and has an optical bandwidth of 36 nm. Multimode inputs to the waveguide gratings are used to flatten their optical passbands, leading to a fourfold decrease in pulse ringing. The device is able to (pre-) compensate dispersion values of 0.2 ps/nm for 300 fs pulses, which is a suitable value for applications in e.g. biomedical multi-photon imaging

A single etch-step fabrication-tolerant polarization splitter

A tolerant single etch-step passive polarization splitter on InP/InGaAsP is designed and fabricated. The device consists of a directional coupler with a wide and a narrow waveguide. Modal birefringence of the third-order modes for transverse electric (TE) and transverse magnetic (TM) polarizations is employed to selectively couple one polarization. Tapering is applied to increase the tolerances. The devices are characterized, and the measurement results show good agreement with the beam-propagation-method simulations: a splitting ratio larger than 95% for a width range of around 100 nm and over a large wavelength range, covering at least the C-ban