Search

Owing to increased performance capabilities over their LED counterparts, Gallium Nitride (GaN) based Laser Diodes (LDs) are becoming more prevalent in several applications, including lighting, visible light communications, medical spectroscopy, and atom cooling. For many of these applications, a tunable, precise wavelength is necessary such that chromatic aberrations are minimized and that specific wavelengths with narrow linewidth can be utilized for atomic transitions or filtered communications systems. This paper discusses one method of achieving single-mode lasing operation in GaN LDs, namely the deeply-etched sidewall grating Distributed Feedback (DFB) LD. Optical characteristics of such devices will be discussed, as well as their feasibility for optical communications.

Monolithic ∼1.55µm colliding-pulse mode-locked AlGaInAs/InP lasers with 3 and 5 quantum wells are compared. The 3 well device emitted pulses at 162GHz, with a width of 0.98ps, energy of 0.16pJ and time-bandwidth product of 0.47.

We report 40 GHz passively mode-locked 1.55 µm AlGaInAs/InP lasers with integrated semiconductor optical amplifiers producing nearly transform limited pulses with a pulse width of 4 ps and a peak power over 550 mW.

A novel 20 GHz 1.55 µm passively colliding-pulse mode-locked AlGaInAs/InP laser was demonstrated with a small RF linewidth (10 kHz), low timing jitter of 218 fs (4–80 MHz) and low divergence angle (14.7° × 27.3°).

Monolithic AlInGaAs compound-cavity lasers for harmonic ML at multi-GHz frequencies have been fabricated and assessed. Optical pulses of ∶ 1 ps long at 160 GHz have been obtained. The optimal cavity and reflector design has been investigated experimentally and theoretically.

Mode-locked laser diodes (MLLDs) are excellent candidates for generating ultrashort high frequency pulses for a number of applications, including optical clocking, sampling, and clock recovery. Although more prone to noise than active MLLDs, passive MLLDs do not require any external electrical oscillator. But many applications for such lasers require highly stable optical pulses with sub-picosecond timing jitter and in this paper we report a technique for reducing the RF phase noise in a passive MLLD. Regenerative mode locking is a technique used to significantly reduce the timing jitter by providing a self-referencing mechanism to continuously correct the phase timing of the pulses [1, 2]. However, many of the current techniques used are based on electrical extraction and high-Q RF filtering of the pulses, which adds several components and considerable system complexity. Here we present a simplified all-optical regenerative mode locking technique which can provide significant reductions in phase noise and timing jitter.

In recent years there has been a high level of interest in the properties of fast semiconductor saturable absorbers operating at λ ∼ 1.5»m. The applications for these include the fabrication of passively modelocked lasers[1] and wavelength conversion of optical data streams through cross-absorption modulation. To enable these effects to be utilised at the highest repetition rates, very fast absorption recovery times are required, in materials that can be conveniently integrated with optical gain elements. Several methods for achieving very short absorption recovery times have been demonstrated such as the inclusion of high densities of crystal defects in the material and the use of intersubband transitions. However, it is not possible to integrate these with gain elements operating at the same wavelength without the use of expensive and technologically demanding epitaxial regrowth processes.