We report a 48-channel 100-GHz tunable laser near 1550 nm by integrating 16 DFB lasers. High wavelength-spacing uniformity is guaranteed by the reconstruction-equivalent-chirp technique, which enables a temperature tuning range below 20 Celsius degree.
Arrays of metallic particles patterned on a substrate have emerged as a promising design for on-chip plasmonic lasers. In past examples of such devices, the periodic particles provided feedback at a single resonance wavelength, and organic dye molecules were used as the gain material. Here, we introduce a flexible template-based fabrication method that allows a broader design space for Ag particle-array lasers. Instead of dye molecules, we integrate colloidal quantum dots (QDs), which offer better photostability and wavelength tunability. Our fabrication approach also allows us to easily adjust the refractive index of the substrate and the QD-film thickness. Exploiting these capabilities, we demonstrate not only single-wavelength lasing but dual-wavelength lasing via two distinct strategies. First, by using particle arrays with rectangular lattice symmetries, we obtain feedback from two orthogonal directions. The two output wavelengths from this laser can be selected individually using a linear polarizer. Second, by adjusting the QD-film thickness, we use higher-order transverse waveguide modes in the QD film to obtain dual-wavelength lasing at normal and off-normal angles from a symmetric square array. We thus show that our approach offers various design possibilities to tune the laser output.
Nanodiamonds hosting colour centres are a promising material platform for various quantum technologies. The fabrication of non-aggregated and uniformly-sized nanodiamonds with systematic integration of single quantum emitters has so far been lacking. Here, we present a top-down fabrication method to produce 30.0$pm$5.4 nm uniformly-sized single-crystal nanodiamonds by block copolymer self-assembled nanomask patterning together with directional and isotropic reactive ion etching. We show detected emission from bright single nitrogen vacancy centres hosted in the fabricated nanodiamonds. The lithographically precise patterning of large areas of diamond by self-assembled masks and their release into uniformly sized nanodiamonds open up new possibilities for quantum information processing and sensing.
Atomic layer graphene possesses wavelength-insensitive ultrafast saturable absorption, which can be exploited as a full-band mode locker. Taking advantage of the wide band saturable absorption of the graphene, we demonstrate experimentally that wide range (1570 nm - 1600nm) continuous wavelength tunable dissipative solitons could be formed in an erbium doped fiber laser mode locked with few layer graphene.
Previously proposed designs of integrated photonic devices have used the intuitive brute force approach or optimization methods that employ parameter search algorithms. However, a small parameter space and poor exploitation of the underlying physics have limited device performance, functionality, and footprint. In this paper, we propose efficient and compact 2D 1xN in-plane-incidence wavelength demultiplexers by using recently developed objective-first inverse design algorithm. Output ports in the presented 1xN photonic devices are located along the transverse to the input channel. Ultra-high device performance was achieved for the specific designs of 1x2, 1x4, and 1x6 wavelength (de)multiplexers with small footprints 2.80 um x 2.80 um, 2.80 um x 4.60 um, 2.80 um x 6.95 um, respectively. We used two approaches to binarization-level-set and binarization-cost-to obtain silicon wavelength demultiplexer considering fabrication constraints. For instance, the transmission efficiency of binarization-cost 1x2 demultiplexer was -0.30 dB for 1.31 um and -0.54 dB at 1.55 um while crosstalk at the operating wavelengths are negligibly small, i.e., -17.80 and -15.29 dB, respectively. Moreover, for the binarization-cost 1x4 demultiplexer, the transmission efficiency values were approximately -1.90 dB at 1.31, 1.39, 1.47, and 1.55 um as the crosstalk was approximately -13 dB. Furthermore, the objective-first algorithm was used to employ our demultiplexers as multiplexers which means the ports that were once used as inputs in demultiplexers are designed to be used as outputs. The inverse design approach that allows for the implementation of more than six output channels together with the proposed functionalities can help develop compact and manufacturable 2D 1xN couplers.
The ever-increasing demand for high speed and large bandwidth has made photonic systems a leading candidate for the next generation of telecommunication and radar technologies. The photonic platform enables high performance while maintaining a small footprint and provides a natural interface with fiber optics for signal transmission. However, producing sharp, narrow-band filters that are competitive with RF components has remained challenging. In this paper, we demonstrate all-silicon RF-photonic multi-pole filters with $sim100times$ higher spectral resolution than previously possible in silicon photonics. This enhanced performance is achieved utilizing engineered Brillouin interactions to access long-lived phonons, greatly extending the available coherence times in silicon. This Brillouin-based optomechanical system enables ultra-narrow (3.5 MHz) multi-pole response that can be tuned over a wide ($sim10$ GHz) spectral band. We accomplish this in an all-silicon optomechanical waveguide system, using CMOS compatible fabrication techniques. In addition to bringing greatly enhanced performance to silicon photonics, we demonstrate reliability and robustness, necessary to transition silicon-based optomechanical technologies from the scientific bench-top to high-impact field-deployable technologies.