Mohammadshahab (Shahab) Abdollahi Defends PhD on Multi‑Wavelength On‑Chip Lasers Systems

Shahab has successfully defended his PhD thesis entitled "Optical Injection in On-Chip Inp Multi-Wavelength Lasers and Its Use for All Optical Signal Processing" under the supervision of Prof. Dr. Martin Virte and Dr. Pablo Marin-Palomo.

Shahab’s research addresses a critical need for faster, energy-efficient signal processing technologies in the era of exploding data traffic. Motivated by the fundamental limitations of traditional optical-electrical-optical (OEO) conversion methods, he explored new ways to harness the rich nonlinear dynamics of multi-wavelength semiconductor lasers under external optical injection.

Among his key achievements, he demonstrated how carefully controlling injection parameters could induce rich nonlinear dynamics unique to multi-wavelength laser systems. Building on these insights, Shahab introduced and analysed the concept of spectral multiplication — showing how injected signals, such as single-sideband (SSB) signals and narrowband frequency combs, could be spectrally multiplied across large frequency offsets, reaching into the terahertz range.

Through systematic experimental and numerical studies, he mapped how factors such as mode coupling, injection strength, modulation frequency, and cavity resonances shape the laser’s response. Shahab also developed techniques to dynamically tailor and phase-lock different parts of the output spectrum, providing new strategies for generating coherent, multi-channel optical signals directly from compact chip-scale lasers.

Shahab’s research demonstrates strong potential for enabling all-optical wavelength conversion, a key function for modern wavelength-division multiplexed (WDM) systems and next-generation optical networks. By eliminating the need for optical-electrical-optical (OEO) conversion, all-optical processing significantly reduces latency, power consumption, and system complexity. Through a detailed study of the nonlinear interactions in multi-wavelength lasers under external optical injection, Shahab’s work lays the groundwork for compact, energy-efficient, and scalable solutions that are critical for meeting the growing demands of high-capacity optical communication networks.

Following the defense, Shahab continues as a Postdoctoral Researcher, focusing on pushing the boundaries of integrated photonics, nonlinear optics, and ultrafast all-optical signal processing.

At B-PHOT, we are proud to celebrate this outstanding achievement and look forward to Shahab’s future contributions to photonics innovation.