The rapid growth of generative artificial intelligence, high-performance computing, and data-center traffic is pushing optical input/output (optical I/O) technology toward much higher bandwidth density and energy efficiency. Dense wavelength-division multiplexing provides a practical route to petabit-per-second interconnects by carrying many wavelength channels in a single fiber or waveguide, but its implementation depends critically on compact, precise, high-power, and scalable multi-wavelength laser sources. Conventional solutions, including microcomb sources, mode-locked lasers, and ordinary distributed-feedback laser arrays, still face difficulties in stable channel spacing, wavelength accuracy, fabrication cost, output power, and large-scale integration. This paper reviews and summarizes a series of studies on the Kunlun light source, a precise multi-wavelength laser technology developed for future optical I/O systems. The central idea is to use REC (reconstructed equivalent chirp) technology to translate the nanometer-scale difficulty of grating fabrication into a micrometer-scale sampling-pattern design that can be realized by low-cost standard lithography. On this basis, the work explores three connected directions: single-waveguide multi-wavelength emission, hybrid integration of multi-port multi-wavelength sources, and ultra-large-scale monolithic laser arrays. Together, these directions address the key requirements of optical I/O: precise wavelength grids, high side-mode suppression, high output power, compact packaging, and manufacturability.

For single-waveguide integration, REC-based distributed-feedback (DFB) lasers were designed by combining linearly chirped sampling gratings with carefully positioned equivalent phase shifts. This design suppresses mode competition inside the cavity and enables several stable lasing wavelengths to be generated from one waveguide. Four-wavelength and six-wavelength devices were demonstrated, with uniform 100 GHz channel spacing, high side-mode suppression, and stable spectral behavior under different injection currents and temperatures. A semiconductor optical amplifier was further integrated with the laser section to improve output power and compensate channel-to-channel power nonuniformity. For multi-port hybrid integration, the work proposed a compact multi-port multi-wavelength laser source that combines an REC-DFB laser array, SCOW (slab-coupled optical waveguide) high-power laser design, a low-loss silicon-nitride 8 x 8 multimode-interference coupler, and photonic wire bonding. The SCOW structure shifts the optical mode away from high-loss regions and supports high-current operation, while an asymmetric phase-shift grating mitigates the influence of random rear-facet phase and preserves single-mode yield. In experiments, the eight DFB lasers showed threshold currents of 54~64 mA and kink-free output powers above 55 mW per channel. When each laser was driven at 200 mA, eight wavelength channels were coupled to eight output ports, verifying the feasibility of a compact, high-power, multi-port light-source module for optical I/O. For ultra-large-scale monolithic arrays, the work combined REC wavelength synthesis with asymmetric multiple-quantum-well gain engineering. By broadening the effective gain bandwidth from less than 60 nm to more than 120 nm, the array design overcame the gain-bandwidth limitation that usually prevents all channels in a wideband array from lasing uniformly. A 150-channel REC-DFB laser array was experimentally realized, covering continuous single-longitudinal-mode emission from 1464.23 nm to 1584.43 nm. All 150 channels exhibited side-mode suppression ratios better than 45 dB, and the measured average channel spacing was 0.81 nm, confirming the high linearity and wavelength-control precision of the REC approach.

The reviewed results show that REC technology provides a unified and scalable route for precise multi-wavelength laser sources in optical I/O. By using sampled grating reconstruction to control wavelength and phase, the method reduces fabrication complexity while maintaining wavelength-spacing accuracy better than the level required by dense wavelength grids. In single-waveguide lasers, it supports compact multi-wavelength emission with stable mode selection. In hybrid integrated modules, it works together with SCOW lasers, silicon-nitride passive circuits, and photonic wire bonding to provide high-power, multi-port outputs with reduced alignment burden. In monolithic arrays, it enables very large channel counts and broad spectral coverage when combined with engineered gain media. These achievements indicate that the Kunlun light source is a promising candidate for low-cost, high-reliability, and high-density optical engines in petabit-per-second optical interconnects. Future work should further improve electro-optic conversion efficiency, thermal management, packaging density, long-term reliability, and compatibility with silicon photonic chiplets. System-level demonstrations that integrate laser arrays, modulators, wavelength multiplexers, drivers, and control circuits will be especially important for moving the technology from device-level validation to practical deployment in next-generation computing infrastructure.