We propose and experimentally demonstrate a novel multi-wavelength DFB laser with high mode stability and uniform spacing for the optical I/O technology. By employing the linearly chirped sampled grating and multiple equivalent π phase shifts among the cavity, the four-wavelength and six-wavelength lasers with 100 GHz spacing are implemented and experimentally validated. The proposed multi-wavelength DFB laser works with high mode stability, high uniform wavelength spacing, and high uniform output power with varied bias currents and operating temperatures. A semiconductor optical amplifier is monolithically integrated to amplify the output and the output power exceeds 25 mW when the current injected into the SOA is 120 mA. Besides, the relative intensity noise of the filtered wavelengths is below -130 dB/Hz for each wavelength, and clear 25 Gb/s NRZ eye grams are obtained for the filtered each wavelength with the external lithium-niobate Mach-Zehnder modulator, which indicates the capability of the proposed structure to be an alternative approach for the multi-wavelength optical sources in DWDM optical I/O links.

A 16-channel electroabsorption modulated tunable multi-wavelength DFB laser array is proposed and experimentally demonstrated. The sixteen DFB lasers, each with a wavelength spacing of 100 GHz, are arranged in a 4 × 4 matrix. The wavelengths are designed using an interleaving scheme to reduce grating crosstalk. The grating is designed and fabricated using the reconstruction equivalent chirp (REC) technique to simplify the grating fabrication and ensure precise wavelength control. The electroabsorption modulator and the tunable multi-wavelength laser array share the same active layer to reduce fabrication complexity and costs. Wavelength tuning is achieved by selecting the active laser without altering the thermoelectric cooler (TEC). Consequently, 16 channels with 100 GHz spacing are obtained, each operating in good single-mode properties with SMSRs of above 45 dB. The average wavelength spacing is 106.1 GHz, and only 6.1 GHz deviated from the design. The semiconductor optical amplifier (SOA) is integrated to compensate for the frequency chirp and amplify the output power, thus enabling long-distance transmission. The output power is amplified to over 18 mW with a 150 mA current injected into the SOA. The 3-dB bandwidth of the EAM exceeds 20 GHz, producing clear 25 Gb/s back-to-back eye diagrams with mask margins over 40% for the 16 channels. With the assistance of the chirp compensation by the SOA, the eye diagrams of the 16 channels remain clear after 10 km of transmission. Due to the superior performance, the proposed device is promising for use in DWDM systems, particularly in applications requiring fast channel switching, such as optical packet switching and NG-PON2 technology.

We propose and experimentally demonstrate tunable narrow-linewidth DFB laser array based on self-injection feedback Technique. The grating of the proposed tunable laser array is fabricated using the reconstruction equivalent chirp (REC) technique, which simplifies the grating fabrication process and improves wavelength precision. AR and HR coatings are applied to the front and rear facets of the lasers to enhance output power. The single-mode yield of the laser array is improved through the implementation of an asymmetric phase shift (APS). Additionally, the slab-coupled optical waveguide (SCOW) structure is employed to reduce linewidth and increase output power. Low-loss coupling between the laser array and the planar lightwave circuits (PLCs) is achieved via photonic wire bonding (PWB) technology. Finally, a wavelength-insensitive fiber optic circulator is used to further narrow the linewidth. Experimental results demonstrate that the proposed laser array achieves an output power exceeding 100 mW and a tuning range greater than 12.8 nm. When tuned with 100 GHz spacing, 16 wavelengths exhibit SMSRs greater than 50 dB. After passing through the optic circulator, the linewidth of the laser array is reduced to less than 7 kHz, approximately 1/50 of the original linewidth. The exceptional performance of the proposed laser array shows great promise as a tunable light source for coherent optical communication systems.

A wavelength-tunable electroabsorption-modulated DFB laser (EML) with performance enhanced by the integrated thin film heater is proposed and experimentally demonstrated. The reconstruction equivalent chirp (REC) technique is used to simplify the grating fabrication and introduce equivalent phase shifts in the cavity to guarantee single-mode operation. The electroabsorption modulator and the DFB laser share identical active layers to decrease the fabrication complexity. A Ti/Pt thin film heater is monolithically integrated near the DFB waveguide to enable wavelength tuning while keeping the temperature of the EAM almost unchanged. Compared to the wavelength tuning by the thermoelectric cooler, the wavelength tuning by the thin-film heater can obtain low loss for the electroabsorption modulator, uniform output power, and uniform modulation performance. As a result, eight wavelengths with a wavelength spacing of 0.5 nm are tuned by the heater, with a thermal tuning efficiency of 5.7 nm/W. The side mode suppress ratios kept above 45 dB and the output power decreased within 2 dB. The integrated SOA can amplify the output power to 27 mW at a bias current of 120 mA. The 3-dB bandwidth of the electroabsorption modulator is above 22 GHz, and clear eye diagrams for both the 10 Gb/s and 25 Gb/s NRZ modulation are obtained for the tuned wavelength. The proposed wavelength-tunable EML provides a solution for the tunable transmitters used in the DWDM systems.

Femtosecond laser two-photon polymerization (TPP) technology, known for its high precision and its ability to fabricate arbitrary 3D structures, has been widely applied in the production of various micro/nano optical devices, achieving significant advancements, particularly in the field of photonic wire bonding (PWB) for optical interconnects. Currently, research on optimizing both the optical loss and production reliability of polymeric photonic wires is still in its early stages. One of the key challenges is that inadequate metrology methods cannot meet the demand for multiphysical measurements in practical scenarios. This study utilizes novel in situ scanning electron microscopy (SEM) to monitor the working PWBs fabricated by TPP technology at the microscale. Optical and mechanical measurements are made simultaneously to evaluate the production qualities and to study the multiphysical coupling effects of PWBs. The results reveal that photonic wires with larger local curvature radii are more prone to plastic failure, while those with smaller local curvature radii recover elastically. Furthermore, larger cross-sectional dimensions contribute dominantly to the improved mechanical robustness. The optical-loss deterioration of the elastically deformed photonic wire is only temporary, and can be fully recovered when the load is removed. After further optimization based on the results of multiphysical metrology, the PWBs fabricated in this work achieve a minimum insertion loss of 0.6 dB. In this study, the multiphysical analysis of PWBs carried out by in situ SEM metrology offers a novel perspective for optimizing the design and performance of microscale polymeric waveguides, which could potentially promote the mass production reliability of TPP technology in the field of chip-level optical interconnection.

Photonic neuromorphic computing based on spiking dynamics has been a promising approach for constructing low-latency and energy-efficient non-von Neumann architecture. However, the system is severely limited by the discrete optical injection and modulation devices. We proposed and demonstrated a true full-integrated spiking neuron based on a monolithic integrated directly modulated laser-distributed feedback laser (DML-DFB) chip. While the directly modulated master laser (DML section) inject the optical stimulus into the integrated slave laser (DFB section), rich neuron-like spiking nonlinear responses are observed, including typical spiking threshold, temporal integration, and refractory period. Huge optical discrete system is integrated to be an InP-based chip with area only 0.25 mm ² . To the best of our knowledge, this is the highest level of integration for current photonic spiking system, which paves the way for realizing large-scale photonic spiking neural network (PSNN) that can handle complex tasks.