Power over fiber
Engineers are examining “power over fiber” systems that send up to about 0.5 W of electrical power through optical fibers using high‑power lasers and photovoltaic receivers. Commenters note these modules are expensive and inefficient compared to copper, but highlight niche advantages: perfect galvanic isolation, operation in high‑voltage or EMI‑heavy environments (e.g., MRI, HV probes, ROVs), and avoiding costly electrical work where fiber already exists. Much of the debate centers on safety of class‑4 laser levels, realistic power budgets for sensors and microcontrollers, and comparisons with alternatives like Power over Ethernet or hybrid fiber‑copper cables.
Cost and industrial context
- Commenters note the optical power converters cost hundreds of dollars each and often have minimum order quantities.
- Many argue this is typical for rugged, certified industrial components (similar to $300 emergency-stop buttons), where long-term availability, reliability, and liability matter more than unit price.
- Others still view it as “too expensive” for most consumer or hobby use.
Power budget and what 0.5 W can do
- The device delivers ~3 V at 180 mA (≈0.54 W), roughly 30–45% efficient depending on operating point.
- Multiple posters stress that 0.5 W is ample for modern low-power electronics: sensors, microcontrollers (including ESP32-class), small LCDs, data loggers, and active probes, especially with capacitors for short power spikes.
- Comparisons are made to daily consumption of several AA batteries; energy is “luxurious” by ultra‑low‑power design standards.
Safety and laser hazards
- The source lasers are around 1.5 W at ~800 nm, placing them in hazardous laser classes.
- Discussion emphasizes: IR is often invisible, blink reflex is ineffective, and even reflections can be dangerous; warnings and interlocks are considered essential.
- Some argue fiber output may diverge quickly and limit burn risk; others counter that polished or shaped fiber tips can still produce very high power density.
- Class 4 lasers and their (limited) weaponization are debated; blinding weapons are noted as banned by treaty.
Efficiency and loss
- Overall optical-to-electrical efficiency (~35%) is viewed as poor compared to copper, but decent versus other isolated power schemes or Qi‑style wireless.
- Some note wasted energy is small in absolute terms for single devices but could add up in large deployments.
Use cases and niche value
- Strong interest for high-voltage isolation (active high‑voltage probes, micro‑HSMs, sensors bonded to HV equipment), MRI/EMI‑hostile environments, and situations where adding copper would trigger costly recertification.
- Underwater and ROV tethers are highlighted: power over fiber can reduce cable weight and drag; similar tech has been demonstrated at hundreds of watts.
- Also mentioned: powering isolated industrial cameras, remote sensors, and potentially POTS‑like phones (with safety concerns).
Comparisons and alternatives
- Compared to PoE (15–100 W) this is far lower power but offers perfect galvanic isolation.
- Hybrid fiber+copper cables and active optical USB/HDMI/DP cables are cited as alternative ways to combine data and power.
- Some discuss sending data and power on separate wavelengths in the same fiber; backscatter interference is a concern for bidirectional links.
Limits and open questions
- Maximum safe power is limited by fiber heating, defects, and potential “runaway” hot spots; industrial laser fibers can carry tens of kW but are highly specialized.
- Transmission distance for this specific product and its bandwidth are not clearly documented in the thread and remain “unclear.”