We fabricated an optical transmitter with high frequency and integrated design based on the flip-chip interconnection technique (Hi-FIT) and assisted extended reach electroadsorption modulator integrated distributed feedback (EADFB) laser (AXEL) for 200-Gbit/s/λ application. The Hi-FIT makes it possible to increase modulation bandwidth thanks to wire-free interconnection and peaking control techniques while the AXEL can increase the optical modulation output power thanks to an integrated semiconductor optical amplifier (SOA). The fabricated Hi-FIT AXEL transmitter has a 3-dB bandwidth of more than 66 GHz. We obtained clear 224-Gbit/s 4-level pulse amplitude modulation (4-PAM) eye diagrams with a chip-output optical modulation amplitude (OMA) of more than +7.9 dBm at distributed feedback (DFB) laser and SOA currents of 70 and 30 mA, respectively.
To overcome the limitation of the small tuning range of 1.3-µm-wavelength distributed Bragg reflector (DBR) lasers using the carrier-plasma effect, we designed a DBR structure with InAlAs carrier confinement layers and an InGaAlAs core layer. We found that the enhanced carrier density and small effective mass of electrons in the core layer of the DBR regions resulted in a wide Bragg wavelength shift. The enhanced refractive-index change due to the new structure enabled us to fabricate the world's first 1.3-µm-wavelength superstructure-grating DBR laser with a quasi-continuous tuning range of over 30 nm.
An InP-based Mach-Zehnder interferometer combined with a metamaterial layer consisting of a split-ring resonator array was constructed to measure the complex permeability of the metamaterial. At a wavelength of 1.5 µm, the metamaterial showed non-unity relative permeability induced by magnetic interaction with propagating light in the device. This method of measurement would be useful to determine constitutive parameters in such waveguide-based photonic devices, allowing us to design photonic integrated circuits that make use of metamaterials.
We fabricated a novel lateral-current-injection-type distributed feedback (DFB) laser with amorphous-Si (a-Si) surface grating as a step to realize membrane lasers. This laser consists of a thin GaInAsP core layer grown on a semi-insulating InP substrate and a 30-nm-thick a-Si surface layer for DFB grating. Under a room-temperature continuous-wave condition, a low threshold current of 7.0 mA and high efficiency of 43% from the front facet were obtained for a 2.0-µm stripe width and 300-µm cavity length. A small-signal modulation bandwidth of 4.8 GHz was obtained at a bias current of 30 mA.
Arsenicals/chemistry , Gallium/chemistry , Indium/chemistry , Lasers , Membranes, Artificial , Phosphines/chemistry , Refractometry/instrumentation , Silicon/chemistry , Equipment Design , Equipment Failure Analysis , Feedback
The modulation bandwidth enhancement of distributed reflector (DR) lasers with wirelike active regions utilizing optical injection locking is demonstrated both theoretically and experimentally. By the rate equation analysis, it is shown that DR lasers with wirelike active regions realize a low optical injection power and a large bandwidth enhancement under small operation currents. Experimentally, the small-signal bandwidth is increased to >15 GHz at a bias current of 5 mA, which is 4 times smaller than that for conventional edge-emitting lasers. A large signal modulation at 10 Gbps is also performed at the same bias current of 5 mA and voltage swing of 0.4 V(pp), and error-free detection was confirmed under the low-power conditions.
Computer Simulation , Lasers, Semiconductor , Lasers , Light , Quantum Dots , Scattering, Radiation , Telecommunications/instrumentation , Computer-Aided Design , Equipment Design , Injections , Signal Processing, Computer-Assisted
