We report the fabrication of a first electro-absorption modulated widely tunable DBR lasers (TEML) based on InGaAlAs multi-quantum well (MQW) material, which is superior than InGaAsP MQWs for the fabrication of both modulators and lasers. The device is fabricated by using butt-joint material growth technology and operates at a wavelength of 1.5 μm. An over 12 nm wavelength tuning range can be obtained. The characteristic temperature of the device is 83 K, which is notably higher than that for a laser based on InGaAsP MQWs. At 25 ℃, the electro-absorption modulator (EAM) of the device has a small signal modulation bandwidth exceeding 27 GHz, which is notably higher than the bandwidth for a TEML device having the same structure but InGaAsP MQW active material. At 25 Gb/s NRZ data modulation, to achieve 10E-10 bit error rate (BER), the power penalty after 5 and 10 km fiber transmission are 1 and 3 dB, respectively. The device is a promising low-cost light source for future high-capacity wavelength division multiplexing (WDM) optical communication systems.

A frequency stabilization scheme for a wideband-tunable optoelectronic oscillator (OEO) based on fundamental and subharmonic RF injection locking is proposed, achieving a tuning range of 2–22 GHz with low phase noise. The injection-locked performance of the OEO using the fundamental RF signal and its 1/n subharmonic is investigated. The fundamental injection locking achieves a phase noise of <−130 dBc/Hz @ 10 kHz offset across the entire tuning range. An examination of phase noise behavior at different subharmonic orders reveals that fundamental and subharmonic injection locking achieve a five-order-of-magnitude improvement in Allan variance (0.1 s) and approximately 40 dB phase noise reduction at a 10 Hz offset from the carrier. This approach leverages the low-phase-noise advantage of the OEO while benefiting from the high stability of low-frequency external RF sources, enabling multi-frequency point frequency stabilization optimization.

We report a 1.3-μm dual-wavelength distributed feedback (DFB) photonic integrated chip with modulation bandwidth enhancement using integrated optical feedback section. The dual-wavelength DFB lasers were realized using the upper separate confinement heterostructure (SCH) selective area growth (SAG) approach. A modified butt-joint technique was also adopted to achieve high-quality active-passive interface and minimize unintentional intra-cavity optical feedbacks. The fabricated photonic chip exhibited stable single mode operations with a wavelength separation of 2.06 nm. The 3-dB modulation bandwidth was enhanced through the photon-photon resonance effect with f_3dB > 17 GHz and open eyes up to 25 Gbit/s for both channels were also obtained. The design can also be scaled up to higher channel counts and higher data rate.

A novel wavelength triplexer based on Channel-Shaped Multimode Interference (C-MMI) structures on the InP platform is proposed for multi-channel integration compatibility in a 50G passive optical network (PON) system. Performance analysis of the proposed device is carried out by using the 3D Beam Propagation Method (3D-BPM), which shows excellent properties with insertion loss < 0.5 dB and low crosstalk < −14 dB for the 1342 nm in the Original band (1260–1360 nm), 1490 nm in the Short wavelength band (1460–1530 nm), and 1577 nm in the Long wavelength band (1565–1625 nm), also known as the OSL wavelengths band. Furthermore, the passbands of the three downlink channels of 1342 nm, 1490 nm, and 1577 nm, reach 14 nm, 20 nm, and 64 nm, respectively, which is wide enough to meet the 50G PON optical line terminal (OLT) requirement. Additionally, the proposed device is extremely compact with a total length of only 448 μm, making it attractive in the monolithic integrated laser chip and OLT packaged module.

This paper describes a technique for characterizing Input/Output (IO) power delivery networks using Vector Network Analyzer (VNA) S₂₁ measurements, which is expanded from the core Power Delivery Networks (PDN) measurement technique we developed. The technique uses the two-port, self-impedance measurement concept for low impedance PDN measurement. It is validated mathematically through network analysis and makes use of an auxiliary test fixture to remove the effect of the channel between measurement points and bumps. Measurements of a sample are presented to show the effectiveness of the methodology.

A differential multi-frequency laser Doppler velocimetry is demonstrated, utilizing the synchronized multimode of a mode-locked distributed Bragg reflector laser. This scheme enables the simultaneous detection of multiple Doppler frequency shifts. Multiple differential Doppler shifts of 0.6 Hz, 1.3 Hz, and 1.9 Hz are obtained, with an average speed of 3.677 mm/s and a standard deviation of 0.122 mm/s, demonstrating a cross-referenced velocity measurement capability. The measurement results are also compared with the dual-frequency laser Doppler velocimetry scheme using electro-optical modulation.