24F OM3 MTP® Loopback
The 24-Fiber OM3 MTP® Loopback Module is a high-density passive multimode fiber optic test solution engineered for comprehensive port verification and system diagnostics in 40G, 100G, and emerging 400G parallel optics environments. This module delivers a controlled, closed optical return path across 24 fiber lanes within a single MTP®-24 interface, enabling simultaneous multi-transceiver testing and full-architecture validation without external cabling infrastructure.
Constructed with laser-optimized OM3 50/125 um multimode fiber featuring an effective modal bandwidth of 2000 MHz-km at 850 nm, this module is optimized for cost-effective high-speed testing in enterprise and data center environments. The aqua-colored connector shell provides immediate visual identification as an OM3 multimode component per TIA-598-C standards. The dual-row MT ferrule design (2×12 fibers) supports flexible mapping strategies including dual-transceiver testing, split-mode configurations, and full 16-lane active architectures. The precision push-pull coupling mechanism ensures rapid, tool-free deployment while maintaining reliable optical contact across all 24 fiber lanes. This module is particularly valuable for brownfield deployments with existing OM3 infrastructure and mixed-fiber environments requiring backward compatibility validation.
Description
2. Key Features
- 24-fiber MTP® connector for high-density 40G/100G/400G multimode testing
- Laser-optimized OM3 50/125 um fiber with 2000 MHz-km EMB at 850 nm
- Dual-row MT ferrule (2×12) enabling simultaneous dual-transceiver testing
- UPC flat polish with precision ceramic ferrule for optimal optical performance
- Enhanced push-pull coupling mechanism with positive retention for high-density panels
- Low insertion loss (<= 0.75 dB max, standard grade) across all 24 lanes
- High return loss (>= 25 dB typical) for clean signal reflection
- Flexible polarity options: Type A, B, C, D (8+8+8 split), or custom mapping
- Aqua connector shell per TIA-598-C for immediate OM3 multimode identification
- LSZH (Low Smoke Zero Halogen) housing with UL 94 V-0 flammability rating
- Dual guide pins for enhanced alignment stability in 24-fiber configuration
- Compatible with QSFP+, QSFP28, QSFP56, QSFP-DD, and CXP transceiver platforms
- Ideal for brownfield deployments and mixed OM3/OM4 infrastructure testing
- Protective dust cap with optional tether for field deployment security
- RoHS and REACH compliant with full material traceability documentation
3. Technical Specifications
3.1 General Parameters
| Parameter | Specification |
| Product Type | MTP® Loopback Module (High-Density Multimode) |
| Fiber Count | 24 Fibers (dual-row MT ferrule, 2×12) |
| Fiber Type | OM3 Multimode 50/125 um (laser-optimized, IEC 60793-2-10 A1a.2) |
| Connector Type | MTP®-24 (Female / Male available) |
| Connector Gender | Female (no guide pins) standard; Male (with guide pins) optional |
| Connector Shell Color | Aqua (OM3 multimode identification per TIA-598-C) |
| Polish Type | UPC (Ultra Physical Contact, flat polish) |
| Polarity | Type A, B, C, D (8+8+8 split), or custom per engineering drawing |
| Housing Material | LSZH (Low Smoke Zero Halogen) thermoplastic, UL 94 V-0 rated |
| Coupling Mechanism | Enhanced push-pull with positive retention |
| Dust Cap | Protective dust cap included; tethered cap optional |
| Guide Pin Diameter | 0.7 mm (male connector), dual guide pins |
| Ferrule Type | 24-fiber MT ferrule (6.4 mm x 2.5 mm, dual-row ceramic) |
| Weight (typical) | 8 g per module (without pigtail) |
| Dimensions (L x W x H) | 52 mm x 12 mm x 8 mm (typical) |
3.2 Optical Performance
| Parameter | Low Loss Grade | Standard Grade | Unit |
| Typical Insertion Loss | 0.20 | 0.35 | dB |
| Maximum Insertion Loss | 0.60 | 1.00 | dB |
| Return Loss | >= 30 | >= 25 | dB |
| Operating Wavelength | 850 / 1300 | 850 / 1300 | nm |
| Lane-to-Lane Uniformity | <= 0.3 | <= 0.5 | dB |
| Cross-Talk Isolation | >= 55 | >= 50 | dB |
3.3 OM3 Fiber Characteristics
| Parameter | Specification |
| Core / Cladding Diameter | 50.0 +/- 2.5 / 125.0 +/- 1.0 um |
| Effective Modal Bandwidth (EMB) @ 850 nm | >= 2000 MHz-km |
| Overfilled Launch Bandwidth @ 850 nm | >= 1500 MHz-km |
| Overfilled Launch Bandwidth @ 1300 nm | >= 500 MHz-km |
| Maximum Attenuation @ 850 nm | 3.5 dB/km |
| Maximum Attenuation @ 1300 nm | 1.5 dB/km |
| Differential Mode Delay (DMD) | Per IEC 60793-1-49 |
| Numerical Aperture (NA) | 0.20 +/- 0.015 |
| Macro-bend Loss @ 850 nm (15 mm, 2 turns) | <= 0.5 dB |
| Jacket Color | Aqua (per TIA-598-C standard) |
| Minimum Bend Radius (short-term) | 30 mm |
| Minimum Bend Radius (long-term) | 15 mm |
| Fiber Count per Row | 12 fibers (2 rows x 12) |
3.4 Transmission Distance Capability
Maximum supported transmission distances for high-speed transceiver types using OM3 fiber:
| Transceiver Type | Data Rate | Max Distance (OM3) | Active Fibers | Modulation |
| 40G-SR4 (QSFP+) | 40 Gbps | 100 m | 8 (4 TX + 4 RX) | NRZ |
| 100G-SR4 (QSFP28) | 100 Gbps | 100 m | 8 (4 TX + 4 RX) | NRZ |
| 200G-SR4 (QSFP56) | 200 Gbps | 70 m | 8 (4 TX + 4 RX) | PAM4 |
| 400G-SR8 (QSFP-DD) | 400 Gbps | 70 m | 16 (8 TX + 8 RX) | PAM4 |
| 400G-SR4.2 (QSFP-DD) | 400 Gbps | 100 m | 8 (4 TX + 4 RX) | PAM4 |
Note: OM3 fiber provides shorter reach compared to OM4 for equivalent transceiver types. For applications requiring maximum distance, consider OM4 or OM5 fiber options.
3.5 Environmental Specifications
| Parameter | Specification |
| Operating Temperature | -40 degC to +75 degC (extended industrial range) |
| Storage Temperature | -40 degC to +85 degC |
| Thermal Shock | -40 degC to +75 degC, 30 cycles per IEC 61300-2-14 |
| Temperature-Humidity Bias | 85 degC / 85% RH, 1000 hours per IEC 61300-2-18 |
| Humidity (operating) | 5% to 95% RH (non-condensing) |
| Altitude | Up to 3,000 m (standard data center deployment) |
| Dust Ingress | IEC 61300-2-41 compliant for harsh environments |
3.6 Dimension Specifications
4. Fiber Mapping & Polarity
The 24-fiber configuration enables versatile mapping strategies to support multiple transceiver architectures and testing scenarios. Proper fiber mapping is critical for valid loopback diagnostics and must align with the target system design.
4.1 Available Polarity Options
4.2 24-Fiber Active Lane Configurations
Different transceiver platforms utilize varying numbers of active fibers from the 24-fiber MTP® connector. Common configurations for OM3 infrastructure:
| Application | TX Lanes | RX Lanes | Unused Fibers | Configuration |
| 400G-SR8 (QSFP-DD) | 1-8 | 17-24 | 9-16 | Full 8-lane active |
| 2x 100G-SR4 | 1-4, 13-16 | 9-12, 21-24 | 5-8, 17-20 | Dual transceiver |
| 2x 40G-SR4 | 1-4, 13-16 | 9-12, 21-24 | 5-8, 17-20 | Legacy equipment |
| 3x 40G-SR4 | 1-4, 9-12, 17-20 | 5-8, 13-16, 21-24 | None | Maximum utilization |
| 400G-SR4.2 | 1-4 | 9-12 | 5-8, 13-24 | 200G/lane PAM4 |
4.3 Dual-Row Ferrule Architecture
The 24-fiber MTP® connector employs a dual-row MT ferrule with precise fiber positioning:
| Row | Fiber Positions | Physical Location | Typical Assignment |
| Row A | 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 | Top row | Primary transceiver TX lanes |
| Row B | 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 | Bottom row | Primary transceiver RX lanes |
The dual guide pins ensure precise alignment between rows A and B, critical for maintaining low insertion loss across all 24 fiber lanes.
Critical: Always verify the exact lane mapping with transceiver vendor documentation. For multi-transceiver configurations (Type D or E), confirm each transceiver’s pinout before procurement. Request and approve internal mapping drawings for custom configurations.
5. Cost-Benefit Analysis
The 24F OM3 MTP® Loopback Module provides significant cost advantages for high-density testing environments compared to individual transceiver testing methods:
| Metric | Individual Testing | 24F OM3 Loopback | Improvement |
| Test Time per Port | 5-10 minutes | 1-2 minutes | 75-80% reduction |
| Equipment Required | Multiple patch cables | Single module | 80% less inventory |
| Labor Cost | 1 technician per test | 1 tech tests multiple ports | 60-70% labor savings |
| Infrastructure | External cabling needed | Self-contained | Zero external cabling |
| Accuracy | Variable by technician | Repeatable, controlled | Higher consistency |
| Storage | Multiple cable types | Single compact module | 90% space reduction |
For a typical 100-port data center deployment, the 24F OM3 loopback module can reduce commissioning time from 8-16 hours to 2-3 hours, representing substantial labor cost savings.
6. Transceiver Compatibility Matrix
Comprehensive compatibility with current multimode transceiver platforms on OM3 infrastructure:
| Form Factor | Interface | Data Rate | Fibers Used | OM3 Compatibility |
| QSFP+ | MTP®-12 | 40 Gbps | 8 | Direct (native), 100m reach |
| QSFP28 | MTP®-12 | 100 Gbps | 8 | Direct (native), 100m reach |
| QSFP56 | MTP®-12 | 200 Gbps | 8 | Direct (native), 70m reach |
| QSFP-DD | MTP®-24 | 400 Gbps | 16 | Direct (SR8), 70m reach |
| QSFP-DD | MTP®-12 | 400 Gbps | 8 | Direct (SR4.2), 100m reach |
| CXP | MTP®-12 x2 | 120 Gbps | 20 | Dual MTP®-12 required |
| CFP2 | MTP®-12 | 100 Gbps | 8 | Direct (native), 100m reach |
7. Standards & Compliance
| Standard | Description |
| IEC 61754-7 | Fibre optic connectors – MTP® connector interface standard |
| IEC 60793-2-10 | Optical fibres – Product specifications – A1a.2 (OM3) |
| TIA-492AAAC | OM3 multimode fiber specification (50/125 um, laser-optimized) |
| TIA-598-C | Optical fiber cable color coding and identification |
| TIA-604-5 | Fiber optic connector intermate ability – MTP® type |
| ISO/IEC 11801 | Generic cabling for customer premises (OM3 class) |
| IEEE 802.3bm | 100 Gb/s Ethernet over multimode fiber |
| IEEE 802.3cm | 400 Gb/s Ethernet over multimode fiber |
| IEC 61300-2-x | Basic test procedures: vibration, shock, thermal, humidity |
| IEC 61300-3-4 | Attenuation / insertion loss measurement method |
| IEC 61300-3-35 | Visual inspection of fiber optic connector end-faces |
| UL 94 V-0 | Flammability rating for housing material |
| RoHS 2011/65/EU | Restriction of Hazardous Substances Directive |
| REACH EC 1907/2006 | Registration, Evaluation, Authorisation of Chemicals |
8. Applications
The 24F OM3 MTP® Loopback Module addresses diverse testing requirements across enterprise networks, data centers, and manufacturing environments:
| Application | Description | Use Case |
| Multi-Transceiver Testing | Simultaneous verification of dual 12-fiber transceiver pairs using single 24-fiber loopback with Type D mapping | Efficiency optimization |
| 400G System Validation | Full 8-lane TX/RX verification for 400G-SR8 QSFP-DD transceivers with lane-level diagnostics | New deployment |
| Brownfield Infrastructure Testing | Performance validation and backward compatibility assessment in existing OM3 fiber plant environments | Upgrade planning |
| Data Center Spine Commissioning | High-density MTP® port validation in spine-leaf architectures before live network deployment | Network rollout |
| Equipment Burn-in | Continuous 24-lane optical loopback for extended reliability testing during factory acceptance procedures | Manufacturing QA |
| Split-Mode Diagnostics | Testing of split-mode transceiver configurations (e.g., 2x 100G-SR4 or 2x 40G-SR4) from single MTP®-24 port | Flexible testing |
| High-Density Panel Verification | Rapid validation of 24-fiber MTP® cassettes and patch panels in fiber distribution frames | Structured cabling |
| Mixed-Fiber Environment Testing | Validation of OM3 to OM4 migration paths and performance margin assessment in mixed-fiber deployments | Infrastructure upgrade |
9. Ordering Information
To place an order or request a quotation, please specify the following parameters:
| Parameter | Options | Default |
| Fiber Count | 24 | 24 |
| Fiber Type | OM3 (50/125 um, laser-optimized multimode) | OM3 |
| Connector Gender | Female (standard), Male (optional) | Female |
| Polish Type | UPC | UPC |
| Polarity | Type A, B, C, D (8+8+8), E (12+12), Custom | Type A |
| Performance Grade | Low Loss, Standard | Standard |
| Dust Cap | Standard (loose), Tethered (attached) | Standard |
| Labeling | Standard, Custom (laser-etched or printed) | Standard |
| Packaging | Individual anti-static bag, foam tray, bulk carton | Individual bag |
| Minimum Order Quantity | 1 pc (sample); 5 pcs (production) | 1 pc |
| Lead Time | Standard: 2 weeks; Custom mapping: 3 weeks | N/A |
Part Number Convention: MTP®24-LB-OM3-[Gender]-[Polish]-[Polarity]-[Grade]-[Options]
Example: MTP®24-LB-OM3-F-UPC-A-STD = 24F OM3 MTP® Loopback, Female, UPC polish, Type A polarity, Standard grade
Example: MTP®24-LB-OM3-F-UPC-D-LL-T = 24F OM3 MTP® Loopback, Female, UPC polish, Type D (8+8+8 split) polarity, Low Loss grade, tethered cap
10. Handling, Storage & Maintenance
10.1 Handling Precautions
- Always use the protective dust cap when the module is not mated. The 24-fiber dual-row ferrule is particularly susceptible to contamination due to high fiber density and small 250 um pitch.
- Inspect the MTP® connector end-face with a fiber inspection microscope (per IEC 61300-3-35) before each insertion. Use minimum 200x magnification to inspect all 24 fibers across both rows.
- Clean the connector end-face using an MTP®-24 specific cleaning tool (cassette cleaner or click cleaner designed for 24-fiber connectors). Standard 12-fiber cleaners will not cover all fibers.
- Do not touch the ferrule end-face with bare fingers. Skin oils, lotions, and particulates degrade optical performance and can cause permanent end-face damage on high-density ferrules.
- Verify the aqua connector shell color matches the target OM3 multimode adapter. Do not mate OM3 connectors with singlemode (yellow/black) or OM1/OM2 (orange/beige) infrastructure.
- Align both guide pins and keying notch correctly before insertion. The 24-fiber connector requires precise alignment due to dual-row ferrule design. Do not force insertion.
- Use anti-static handling procedures in ESD-sensitive environments. The MTP® connector housing can accumulate static charge during handling.
- For multi-transceiver configurations (Type D/E), verify each transceiver’s pinout matches the loopback mapping before testing.
10.2 Storage Requirements
- Store in original anti-static packaging in a clean, dry, temperature-controlled environment.
- Maintain storage temperature between -40 degC and +85 degC. Avoid rapid temperature changes that may cause condensation on the ferrule end-face.
- Maintain humidity below 85% RH during storage to prevent moisture absorption in the ferrule material.
- Avoid exposure to direct sunlight, UV radiation, and corrosive atmospheres (H2S, SO2, chlorine, salt spray) during storage.
- Do not stack more than 10 modules vertically to prevent housing deformation and guide pin damage.
- Store in original packaging until ready for use. Do not remove dust caps until immediately before mating.
- For long-term storage (> 6 months), inspect dust cap integrity before use.
10.3 Maintenance Schedule
| Condition | Action Required |
| Before each use | Visual inspection with 200x microscope; clean if contamination detected |
| After 100 mating cycles | Detailed end-face inspection per IEC 61300-3-35 Grade B |
| After 500 mating cycles | Full inspection; measure insertion loss; re-polish if degradation observed |
| Annual (if stored) | Visual inspection; verify dust cap integrity; check for housing discoloration |
| After field incident | Immediate inspection; test insertion loss on all 24 lanes; replace if any lane out of spec |
| After cleaning | Re-inspect end-face; verify no cleaning residue remains on ferrule |
10.4 Troubleshooting Guide
Common issues and resolution procedures for 24F OM3 MTP® Loopback Module:
| Symptom | Probable Cause | Resolution |
| High insertion loss on multiple lanes | End-face contamination or damage | Clean end-face with MTP®-24 cleaner; inspect with microscope |
| Inconsistent loss across lanes | Uneven ferrule contact or contamination | Re-seat connector; clean end-face; verify adapter alignment |
| No signal on specific lanes | Incorrect polarity or mapping | Verify polarity type matches transceiver; check mapping drawing |
| Intermittent connection | Insufficient insertion force or guide pin misalignment | Ensure full insertion until click; verify guide pins not bent |
| High return loss | End-face contamination or polish degradation | Clean end-face; inspect for scratches; replace if damaged |
