Long-term Contractors Role (Outside IR35) working through one of our approved suppliers at VIAVI VIAVI (NASDAQ: VIAV) is a blue-chip global enterprise has a 90+ year history of technical innovations that have evolved to keep pace and address our customer’s most pressing business issues. We make equipment, software, and systems that help to plan, deploy, certify, monitor, and optimize all kinds of networks - like those for mobile phones, service providers, large businesses, and data centres. And we are also at the forefront of optical security – we bend light to develop and deliver optical solutions that provide security to the world’s currencies and safety and performance applications for consumer electronics and spectrometry. We are the people behind the products that help keep the world connected – at home, school, work, at play, and everywhere in between. VIAVI employees are fierce about supporting customer success and we welcome people who bring their best every day to the company - to question, to collaborate and to push for solutions that will delight our customers. Duties & Responsibilities: Are you passionate about building cutting-edge AI systems that go beyond the ordinary? We’re looking for a Senior AI Developer to lead the design and deployment of production-grade AI solutions that combine LLMs, agentic AI, graph neural networks, and knowledge graphs to deliver real-world impact. Key Responsibilities • Design, pre-train, fine-tune and evaluate domain-specific LLMs; incorporate Retrieval-Augmented Generation (RAG) and prompt-engineering techniques to maximise factual accuracy and controllability. • Build and orchestrate multi-agent architectures with frameworks such as AutoGen, LangGraph, CrewAI and LangChain to enable autonomous task planning, tool use and self-improvement. • Experience and / or knowledge in AI safety techniques. • Implement real-time and batch inference services; expose LLM/agent capabilities through secure REST/gRPC or event-driven APIs. • Construct and maintain enterprise-scale knowledge graphs that feed ranking, recommendation and search pipelines. • Develop and optimise graph-neural-network models for link prediction, node classification and reasoning over structured and semi-structured data sets. Pre-Requisites / Skills / Experience Requirements: • MSc/PhD in Computer Science, Machine Learning, Mathematics or related field, from a reputable University or equivalent industry experience. • Extensive software/ML engineering skills; with hands-on with deep-learning frameworks (PyTorch, TensorFlow, JAX) and distributed training on top of Python language. • Demonstrable experience pre-training or extensively fine-tuning LLMs (GPT, Llama, Mistral, etc.) on multi-billion-token corpora, including RLHF or DPO techniques. • Production experience with agentic frameworks and autonomous AI agents that learn and adapt in real-world environments. • Hands-on knowledge of GNN libraries (PyTorch Geometric, DGL, Deep Graph Library) and graph databases (Neo4j, TigerGraph, Neptune). • Proven ability to architect data pipelines with Spark/Flink/Databricks and deploy on AWS, GCP or Azure using Kubernetes and Terraform. • Strong collaboration and team working skills, including cross-functionally, with the ability to establish and maintain effective relationships across all levels Desirable: • Experience optimising transformer models (quantisation, pruning, distillation). • Contributions to open-source GenAI projects, patents or peer-reviewed publications. Why Join Us? • Work on next-gen AI systems that push the boundaries of autonomy and intelligence. • Collaborate with a world-class team of engineers, researchers, and innovators. • Influence the future of AI in a high-impact, fast-paced environment. • Enjoy a culture of curiosity, creativity, and continuous learning.