Demonstration of a self-pulsing photonic crystal Fano laser

Abstract

Semiconductor lasers in use today rely on mirrors based on the reflection at a cleaved facet or Bragg reflection from a periodic stack of layers. Here, we demonstrate an ultra-small laser with a mirror based on the Fano resonance between a continuum of waveguide modes and the discrete resonance of a nanocavity. The Fano resonance leads to unique laser characteristics. Since the Fano mirror is very narrow-band compared to conventional lasers, the laser is single-mode and in particular, it can be modulated via the mirror. We show, experimentally and theoretically, that nonlinearities in the mirror may even promote the generation of a self-sustained train of pulses at gigahertz frequencies, an effect that was previously only observed in macroscopic lasers. Such a source is of interest for a number of applications within integrated photonics.Keywords: Laser, Photonic-crystal, Fano resonance, Nonlinear optics, Nanocavity, Self-pulsation Conventional semiconductor lasers mirrors are based on a cleaved facet [1] or a Bragg grating, or a two-dimensional grating resonance [2][3][4][5][6][7][8]. In this work, we demonstrate a new concept for lasers, an ultra-small laser with a mirror based on the Fano resonance between a continuum of waveguide modes and the discrete resonance of a nanocavity. The rich physics of Fano resonances [9] has recently been explored in a number of different photonic and plasmonic systems [10,11]. The Fano resonance leads to unique laser characteristics and furthermore represents a very rich dynamical system, which is still to be explored. In particular, since the Fano mirror is very narrow-band compared to conventional lasers, the laser is single-mode and it can be modulated via the mirror. We show, experimentally and theoretically, that nonlinearities in the mirror may even promote the generation of a self-sustained train of pulses at gigahertz frequencies, an effect that was previously only observed in macroscopic lasers [12][13][14][15].The photonic crystal Fano laser (FL) concept is illustrated in Fig. 1(a). The laser cavity is composed of a linedefect waveguide in a photonic crystal (PhC) membrane and two mirrors. The left mirror is a conventional PhC mirror, realized by blocking the PhC waveguide (WG) with air holes [16]. In contrast, the right mirror is due to a Fano interference between the continuum of waveguide modes and the discrete resonance of a side-coupled nanocavity [17]. At resonance, the paths of light through the nanocavity and through the waveguide interfere destructively, leading to a high reflectivity, see Fig. 1(b). If the quality factor (Q-factor) of the nanocavity is dominated by its coupling to the waveguide, rather than by intrinsic losses, the maximum reflectivity of the Fano mirror approaches unity, which is the basis for its use as a laser mirror (see Appendix A.1.). This FL concept was suggested in [18] where it was highlighted that, if such a laser could be realized, it should enable modulation not limited by the relaxation oscillations generic to lasers. Here, we ...

Self-consistent Maxwell-Bloch model of quantum-dot photonic-crystal-cavity lasers

“…In 1994, Dowling et al proposed a one-dimensional (1D) PC operating near the photonic band edge [2], making use of slow-light modes to increase the power emitted by such lasers, which has been one of the limitations of microcavity lasers [3]. Experimentally, slow-light band edge lasers have now been demonstrated in both two-dimensional (2D) [4][5][6][7][8][9][10][11][12] and three-dimensional (3D) [13][14][15] architectures, while over the past decade, significant progress has been made in the optimization of these lasers [15][16][17][18], allowing for the investigation of new operation regimes such as single emitter lasing [19], ultrahigh speed modulation [20], and self-pulsing [21]. To directly model the optical properties of open-system microcavity structures, finite-difference time-domain (FDTD) techniques are often employed since such open cavities support quasinormal modes (QNMs) that have a finite lifetime due their coupling to a continuum of modes with outgoing boundary conditions [22].…”

Theory of Self‐pulsing in Photonic Crystal Fano Lasers

“…Coupled‐cavity structures can also readily be realized, which has been shown to give rise to rich dynamical properties . Recently a new type of photonic crystal laser was demonstrated, where one of the laser mirrors is due to a Fano resonance between a continuum of waveguide modes and a side‐coupled nanocavity. It was shown that this so‐called Fano laser has a regime of operation, where it generates a high‐repetition‐rate train of short optical pulses, attributed to a mirror reflectivity that increases with laser intensity .…”

“…Recently a new type of photonic crystal laser was demonstrated, where one of the laser mirrors is due to a Fano resonance between a continuum of waveguide modes and a side‐coupled nanocavity. It was shown that this so‐called Fano laser has a regime of operation, where it generates a high‐repetition‐rate train of short optical pulses, attributed to a mirror reflectivity that increases with laser intensity . The realization of ultra‐compact lasers that generate short optical pulses are of interest for applications, e.g., in on‐chip optical signal processing.…”

Fano resonances in a photonic crystal covered with a perforated gold film and its application to bio-sensing

“…We show that this interaction results in the Fano resonance, which is a typical sign of the interaction of high-quality dark and lowquality bright modes. In spite of the fact that the research of Fano resonance in photonic and plasmonic structures is a hot topic now [13][14][15][16][17][18], we do not know any investigation devoted nanoslits (Some figures may appear in colour only in the online journal)…”