Design of widely tunable semiconductor lasers and the concept of binary superimposed gratings (BSG's)

Abstract

We propose a new concept of binary superimposed gratings (BSG's) as multiwavelength grating reflectors and show it as an effective structural improvement over the existing designs, to both the fabrication process and device performance. We also present a study of key design issues for widely tunable lasers based on grating mirrors with a comb-like reflection spectrum and summarize simple design rules for the grating part of the laser, based on analytical and numerical analysis. The binary supergrating consists of elements of equal size whose refractive index is allowed to be one of two possible values, which are sequenced according to a binary optics formalism to effect a spatial superposition of multiple sets of single-frequency gratings, and its implementation is well within the standard ebeam lithography limits. The calculations of lasing frequency, mode, and side-mode suppression ratio of the tunable laser are formulated and presented along with numerical examples.

Monolithic wide tunable laser diodes for gas sensing at 2100 nm

“…A binary superimposed grating structure [9] can be seen as a superposition of several DFB grating structures. Different algorithms for the generation of a multiple-wavelength grating are in use.…”

Programmable spectral design using the binary supergrating (BSG)

“…The BSG's guided-wave binary form is shared with our prior Binary Superimposed Grating, from which it has evolved [6], and may comprise nearly any aperiodic two-level modulation of the propagation parameter (effective index). Regardless of its exact form, binary modulation proves more readily implementable than analog counterparts due to its compatibility with standard (binary) lithographic techniques and its required characterization of only two structural features.…”

Extraction of guided modes from organic emission layers by compound binary gratings

“…These structures are comprised of the superposition of multiple gratings with different periods. Compound gratings were investigated, e.g., with regard to their diffraction properties [9,10] and their use as multiwavelength grating reflectors [11], bidiffractive grating couplers [12,13], and effective selective absorbers [14]. Metal gratings with two frequency components have been shown to produce a band gap for surface plasmon polaritons that is observable in outcoupled light [15,16].…”