Across emerging technology domains, a familiar narrative keeps repeating itself. In Extended Reality (XR), progress is often framed as a race toward ever more powerful GPUs. In wireless research, especially around 6G, attention gravitates toward faster transistors and higher carrier frequencies in the terahertz (THz) regime. In both cases, this framing is misleading. The real constraint is no longer raw compute or device-level performance. It is system integration. This is not a subtle distinction. It is the difference between impressive laboratory demonstrations and deployable, scalable products.
XR Has Outgrown the GPU Bottleneck
In XR, GPU capability has reached a point of diminishing returns as the primary limiter. Modern graphics pipelines, combined with foveated rendering, gaze prediction, reprojection, and cloud or edge offloading, can already deliver high-quality visual content within reasonable power envelopes. Compute efficiency continues to improve generation after generation. Yet XR has failed to transition from bulky headsets to lightweight, all-day wearable glasses. The reason lies elsewhere: optics, specifically waveguide-based near-eye displays.
Waveguides must inject, guide, and extract light with high efficiency while remaining thin, transparent, and manufacturable. They must preserve colour uniformity across wide fields of view, provide a sufficiently large eye-box, suppress stray light and ghosting, and operate at power levels compatible with eyewear-sized batteries. Today, no waveguide architecture geometric (reflective), diffractive, holographic, or hybrid solves all these constraints simultaneously. This reality leads to a clear conclusion: XR adoption will be determined by breakthroughs in waveguides, not GPUs. Rendering silicon is no longer the pacing factor; optical system maturity is.
The Same Structural Problem Appears in THz and 6G
A strikingly similar pattern is emerging in terahertz communication research for 6G. On paper, THz promises extreme bandwidths, ultra-high data rates, and the ability to merge communication and sensing on a single platform. Laboratory demonstrations routinely showcase impressive performance metrics. But translating these demonstrations into real-world systems has proven far harder than anticipated. The question is no longer whether transistors can operate at THz frequencies; they can, but whether entire systems can function reliably, efficiently, and repeatably at those frequencies.
According to Vijay Muktamath, Founder of Sensesemi Technologies, the fundamental bottleneck holding THz radios back from commercialisation is system integration. Thermal management becomes fragile, clock and local oscillator integration grows complex, interconnect losses escalate, and packaging parasitics dominate performance. Each individual block may work well in isolation, but assembling them into a stable system is disproportionately difficult. This mirrors the XR waveguide challenge almost exactly.
When Integration Becomes Harder Than Innovation
At THz frequencies, integration challenges overwhelm traditional design assumptions. Power amplifiers generate heat that cannot be dissipated easily at such small scales. Clock distribution becomes sensitive to layout and material choices. Even millimetre-scale interconnects behave as lossy electromagnetic structures rather than simple wires.
As a result, the question of what truly limits THz systems shifts away from transistor speed or raw output power. Instead, the constraint becomes whether designers can co-optimise devices, interconnects, packaging, antennas, and thermal paths as a single electromagnetic system. In many cases, packaging and interconnect losses now degrade performance more severely than the active devices themselves. This marks a broader transition in engineering philosophy. Both XR optics and THz radios have crossed into a regime where system-level failures dominate component-level excellence.
Materials Are Necessary, But Not Sufficient
This raises a critical issue for 6G hardware strategy: whether III–V semiconductor technologies such as InP and GaAs will remain mandatory for THz front ends. Today, their superior electron mobility and high-frequency performance make them indispensable for cutting-edge demonstrations.
However, relying exclusively on III–V technologies introduces challenges in cost, yield, and large-scale integration. CMOS and SiGe platforms, while inferior in peak device performance, offer advantages in integration density, manufacturability, and system-level scaling. Through architectural innovation, distributed amplification, and advanced packaging, these platforms are steadily pushing into higher frequency regimes. The most realistic future is not a single winner, but a heterogeneous architecture. III–V devices will remain essential where absolute performance is non-negotiable, while CMOS and SiGe handle integration-heavy functions such as beamforming, control, and signal processing. This mirrors how XR systems offload rendering, sensing, and perception tasks across specialised hardware blocks rather than relying on a single dominant processor.
Why THz Favours Point-to-Point, Not Cellular Coverage
Another misconception often attached to THz communication is its suitability for wide-area cellular access. While technically intriguing, this vision underestimates the physics involved. THz frequencies suffer from severe path loss, atmospheric absorption, and extreme sensitivity to blockage. Beam alignment overhead becomes significant, especially in mobile scenarios. As Mr Muktamath puts it, “THz is fundamentally happier in controlled environments. Point-to-point links, fixed geometries, short distances, that’s where it shines.”
THz excels in short-range, P2P links where geometry is controlled and alignment can be maintained. Fixed wireless backhauls; intra-data-centre communication, chip-to-chip links, and high-resolution sensing are far more realistic early applications. These use cases resemble the constrained environments where XR has found initial traction in enterprise, defence, and industrial deployments— rather than mass consumer adoption.
Packaging: The Silent Dominator
Perhaps the clearest parallel between XR waveguides and THz radios lies in packaging. In XR, the waveguide itself is the package: it dictates efficiency, form factor, and user comfort. In THz systems, packaging and interconnects increasingly dictate whether the system works at all. Losses introduced by packaging can erase transistor-level gains. Thermal resistance can limit continuous operation. Antenna integration becomes inseparable from the RF front-end. This has forced a shift from chip- centric design to electromagnetic system design, where silicon, package, antenna, and enclosure are co-designed from the outset.
Communication and Sensing: Convergence with Constraints
THz also revives the idea of joint communication and sensing on shared hardware. In theory, high frequencies offer exceptional spatial resolution, making simultaneous data transmission and environmental sensing attractive. In practice, coexistence introduces non-trivial trade-offs.
Waveform design, dynamic range, calibration, and interference management all become more complex when reliability and throughput must be preserved. The most viable path is not full hardware unification, but carefully partitioned coexistence, with shared elements where feasible and isolation where necessary. This echoes XR architectures, where sensing and rendering share infrastructure but remain logically separated to maintain performance.
A Single Lesson Across Two Domains
XR waveguides and THz radios operate in different markets, but they are constrained by the same fundamental truth: the era of component-led innovation is giving way to system-led engineering. Faster GPUs do not solve optical inefficiencies. Faster transistors do not solve packaging losses, thermal bottlenecks, or integration fragility.
As Mr. Muktamath aptly concludes, “The future belongs to teams that can make complex systems behave simply, not to those who build the most impressive individual blocks.” The next generation of technology leadership will belong to organisations that master cross-domain co-design across devices, packaging, optics, and software. Manufacturability and yield as first-order design constraints, Thermal and power integrity as architectural drivers and Integration discipline over isolated optimisation. In both XR and THz, success will not come from building the fastest block, but from making the entire system work reliably, repeatedly, and at scale. That is the real frontier now.
