Spectral amplitude and phase measurement of a 40 GHz free-running quantum-dash modelocked laser diode

Abstract

We present a linear self-referenced measurement of the spectral amplitude and phase of a free-running quantum-dash modelocked laser diode. The technique is suitable for measuring optical signals with repetition rates up to 100 GHz. In contrast to many other linear techniques it requires no external electronic clock synchronized to the signal under test. Using this method we are able to compensate for the intracavity dispersion of the diode to demonstrate 500 fs pulses at a repetition rate of 39.8 GHz. We also use the technique to characterize the dependence of the diode's intracavity dispersion on the applied current.

Time-Domain Traveling-Wave Analysis of the Multimode Dynamics of Quantum Dot Fabry–Perot Lasers

“…The measurements of the spectral phase using stepped heterodyne [44] or generalized multi-heterodyne [45] techniques is an important step in the characterization of a multi-mode FP laser. If the mode phases are constant in time and if they follow a parabolic profile versus the mode pulsation, then it is possible to compensate the corresponding Group Delay Dispersion (GDD) using a standard single mode fiber of suitable length in order to obtain a pulse train at the output of the system [10], [13], [46].…”

Mode coherence measurements across a 15 THz spectral bandwidth of a passively mode-locked quantum dash laser

“…QDash semiconductor modelocked lasers are a promising technology fit owing to their square shaped broadband optical spectrum, low power requirements and mm scale device footprint [5,6]. Previous measurements of these types of lasers have shown a square spectral distribution with a full-width half maximum (FWHM) of 1.7 THz [7]. The optical pulses from this QDash laser were shown to be 490 fs in duration, only 15 fs off the transform limit.…”

High performance mode locking characteristics of single section quantum dash lasers

“…with n Φ being a constant. Moreover, the n Φ should all have the same value and could be written without the subscript provided the total dispersion inside the laser cavity is independent of n throughout the entire pulse spectrum, as suggested from experimental work on different types of semiconductor lasers [5,[13][14][15]. Hence, by integrating Eq.…”

“…However, the phase correlation and the beating frequency locking in these devices come at the expense of a value of 0 Φ ≠ , which will be determined by the nonlinear multi-wave parameters coupling the lasing modes [6]. This explains the usually high values of time bandwidth product (TBP) measured in single section mode locked lasers and, in some cases, the need of external dispersion compensation in order to obtain near transform limited pulses [5,13]. Indeed, by making terms do not affect the shape of ( ) I t , we can write:…”