Ling Lu

Experimental characterization of the optical loss of sapphire-bonded photonic crystal laser cavities

Sapphire-bonded photonic crystal laser cavities with varying number of photonic crystal periods were studied in order to determine the optical loss in these cavities. The lasing threshold increases as the number of lattice periods decreases, and the quality factors of these cavities were calculated from the lasing threshold data. Continuous-wave operation was achieved for cavities with eight or more cladding periods

Spectral properties of photonic crystal double heterostructure resonant cavities

Spectral properties of photonic crystal double-heterostructure resonant cavities were investigated using the three-dimensional finite-difference time-domain method. Bound state formation associated with dispersion minima is observed as well as Fabry-Perot resonances associated with the waveguide cladding

120μW peak output power from edge-emitting photonic crystal double-heterostructure nanocavity lasers

As an attempt to collect more in-plane emission power out of wavelength size two-dimensional photonic crystal defect lasers, edge-emitting photonic crystal double-heterostructure quantum well membrane lasers were fabricated by shortening the number of cladding periods on one side. 120μW peak output power was collected from the facet of the single mode laser at room temperature. Laser efficiencies were analyzed and agree very well with three-dimensional finite-difference time-domain modeling.

Double-heterostructure photonic crystal lasers with lower thresholds and higher slope efficiencies obtained by quantum well intermixing

In order to reduce the optical absorption loss, an array of double-heterostructure photonic crystal microcavity lasers was fabricated in which much of the photonic crystal mirror region was disordered by quantum well intermixing. In characterizing these devices, we obtained more than a factor of two increase in slope efficiencies and more than 20% reduction in threshold pump powers compared to devices that were not intermixed.

Room temperature InGaSb quantum well microcylinder lasers at 2μm grown monolithically on a silicon substrate

Room-temperature photopumped lasing operation near 2.0mum is reported from III-Sb microcylinders grown monolithically on silicon. High quality epitaxy is enabled by an interfacial misfit array. Growth, fabrication and device characterization is discussed

60 microWatts of Fiber-Coupled Peak Output Power from an Edge-Emitting Photonic Crystal Heterostructure Laser

An array of double-heterostructure photonic crystal QW membrane lasers was fabricated in which number of cladding periods was varied. 60 muW peak output power was collected from the facet of one device by a bare fiber.

Microdisk laser linewidth and spontaneous emission rate enhancement

An increase in the spectral width of microdisk laser spectra biased slightly above threshold is experimentally observed, and an increase in spontaneous emission rate in devices with small optical mode volume is demonstrated.

Two-Dimensional Photonic Crystal Micro-Cavities for Chip-Scale Laser Applications

1.1 Photonic crystals In this chapter we will focus on two-dimensional photonic crystal devices and emphasize their use as building blocks in photonic integrated circuits with applications in high bandwidth optical communication systems. In particular we will discuss recent progress in designing high quality (Q) factor resonant cavities for building efficient microand nanocavity lasers. The first section will provide a brief overview of two-dimensional photonic crystals and motivate their use in photonic integrated circuits. This will be followed by a first principles derivation of the role of the Q factor in estimating laser threshold. We will then focus on the photonic crystal heterostructure cavity due to its exceptionally large Q factor. Its spectral and modal properties will be discussed, and its use as a high output power edge-emitting laser will be presented. We conclude with remarks on continuous wave laser operation via heat sinking lower substrates and the issue of out-of-plane loss. The term photonic crystal refers to any structure with a periodic variation in its refractive index (John, 1987; Yablonovitch et al., 1991; Joannopoulos et al., 1995). The periodicity can be in one, two or three spatial dimensions and can introduce a photonic bandgap (a range of frequencies for which electromagnetic radiation is non-propagating) with the same dimensionality. The bandgap arises due to Bragg reflection and occurs when the spatial periodicity has a length scale approximately one half that of the incident electromagnetic radiation. This same phenomenon gives rise to the electronic bandgap in semiconducting materials. Examples of photonic crystal structures with periodicity in varying spatial dimensions are shown in Figure 1. One dimensional photonic crystals have found many technology applications in the form of Bragg reflectors which are part of the optical feedback mechanism in distributed feedback lasers (Kogelnik & Shank, 1971; Nakamura et al., 1973) and vertical cavity surface emitting lasers (Soda et al., 1979). Two and three dimensional photonic crystals have been the subject of intense research recently in areas related to sensing (Loncar et al., 2003; Chow et al., 2004; Smith et al., 2007), telecommunications (Noda et al., 2000; McNab et al., 2003; Bogaerts et al., 2004; Notomi et al., 2004; Noda et al., 2000; Jiang et al., 2005; Aoki et al., 2008), slow light (Vlasov et al., 2005; Krauss, 2007; Baba & Mori, 2007; Baba, 2008) and quantum optics (Yoshie et al., 2004; Lodahl et al., 2004; Englund et al., 2005).

Photonic crystal heterostructure lasers

This presentation will discuss the use of photonic crystal heterostructure resonant cavities in microcavity lasers. The discussion of the experimental work will focus on the use of intermixing to reduce the optical losses in the photonic crystal mirrors, the demonstration of larger output powers, and an investigation of gain compression. The theoretical discussion will focus on cavity spectroscopy, the effect of the index of refraction of the substrate, and a calculation of the threshold gain in these devices.

Room Temperature InGaSb Quantum Well Microcylinder Lasers at 2 μm Grown Monolithically on a Silicon Substrate

Room-temperature photopumped lasing operation near 2.0 μm is reported from III-Sb microcylinders grown monolithically on silicon. High quality epitaxy is enabled by an interfacial misfit array. Growth, fabrication and device characterization is discussed.