Direct answer
Hollow-core fiber guides light predominantly in a hollow region rather than a solid glass core. It can reduce propagation delay, but does not establish a drop-in replacement for any 400G/800G cord. Review the route, HCF-to-SMF transitions, equipment support, wavelength range and complete-link tests.
HCF describes a guiding structure
Microsoft's 2022 technology note contrasts its air-core approach with conventional solid glass cores. “HCF” alone does not identify a connector, fiber count or purchasable assembly configuration.
Multicore fiber concerns multiple cores within one cladding; MPO concerns a multi-fiber connector. Keep guiding structure, physical fiber count and connection system in separate drawing fields.
This guide supports inter-datacenter and latency-sensitive route reviews. It makes no claim that ARRANEX supplies HCF or matches a third-party experiment's performance.
| Term | What it identifies | What remains unspecified |
|---|---|---|
| HCF | Hollow guiding region and microstructure | Connector, equipment support and complete-link behavior |
| Solid-core SMF | Solid-glass single-mode fiber category | Every parameter of an individual model |
| MCF | Multiple cores in one cladding | Direct compatibility with ordinary MPO |
| MPO | Multi-fiber connection system | Fiber material and guiding structure |
Faster propagation is not the same percentage of lower latency
Microsoft's cited note describes propagation 47% faster than standard silica glass for its technology. That statement does not mean 47% higher service throughput or 47% lower total latency.
For an explicit same-length calculation, t = L/v. Assuming speed becomes 1.47 times the original, propagation time becomes 1/1.47, approximately 68% of the original, or about 32% lower. This illustrates the denominator; it predicts no particular HCF route.
End-to-end service delay also includes route length and equipment processing. Define measurement endpoints, one-way versus round-trip delay, instrumentation and traffic conditions before comparing proposals. Equal-length fiber samples do not establish the improvement on a complete business route.
Read deployment and loop experiments separately
Azure's 2025 deployment report discusses metro datacenter interconnection within a developed system ecosystem. It is evidence for that implementation, not blanket transceiver compatibility.
The 2025 Microsoft long-haul paper uses an approximately 360 km recirculating loop to investigate full-C-band transmission and discusses gas-absorption conditions. Accumulated loop transmission distance is not an installed commercial route of the same physical length.
Retain fiber design, topology, amplification and test conditions when using research. Demonstrated capabilities inform evaluation; project acceptance still requires evidence from the intended equipment and path.
Review every HCF-to-SMF transition
| Review item | Evidence requested | Insufficient shortcut |
|---|---|---|
| Route and objective | Actual length and latency reference points | Equal-length speed ratio |
| HCF section | Model, operating band, cable and test evidence | Best research attenuation |
| HCF/SMF transition | Components, joining method, loss and reflection | Similar connector appearance |
| Equipment | Exact part numbers, band and supported setup | 400G/800G label |
| Acceptance | Complete loss, delay, communication and maintenance tests | Bare-fiber or loop result |
| Operations | Test settings, spares and repair method | All legacy settings unchanged |
Draw every HCF/SMF boundary and assign its delivery and acceptance ownership. A transition component does not by itself constitute system approval; include its optical evidence in the path budget.
For mixed routes, confirm propagation parameters used for length and delay measurement. The solution owner should establish whether legacy SMF instrument settings remain valid. Missing information supports a controlled sample evaluation, not filling a specification with a promotional percentage.
Procurement FAQ
- Is HCF simply a hollow plastic cable? The name describes optical guidance, not jacket or cable material. Read the actual construction.
- Does 47% faster mean 47% less delay? At equal length, time is inversely proportional to speed, giving about 32% less propagation time under that assumption.
- Can every 800G module connect directly? Equipment and transition support need explicit evidence.
- Does loop distance equal installed route length? No. Separate physical loop length from accumulated propagation distance.
- Can ordinary SMF joining procedures be copied? Obtain the specific HCF solution's joining, testing and maintenance requirements.
Related products and reading
- Datacenter interconnect review
- Conventional MPO trunk assemblies
- MCF versus MPO
- Propagation delay and skew
The links below cover existing conventional interconnects for interface and path review; they do not imply HCF supply.
Contact an engineer
Prepare endpoint drawings, path requirements or existing test records and contact an engineer to discuss assembly configuration and verification scope.
Sources and review date
- Microsoft 2022 HCF technology note
- Azure HCF network deployment report, 2025
- Microsoft 2025 HCF long-haul experiment
Sources checked on 2026-10-23. References describe general technology or specific third-party configurations, not ARRANEX performance, certification or supply. Purchasing checklists are editorial recommendations; assumed examples are not test results.
Sources checked: 2026-10-23