Hardened fiber optic connector with pre-compressed spring

1. A fiber optic connector comprising:

a plug body having a plug end;

a connector core that mounts within the plug body, the connector core including a ferrule subassembly having a ferrule, a ferrule hub that attaches to the ferrule, a spring holder and a connector spring, wherein the spring holder is coupled to the ferrule hub to allow the ferrule and the ferrule hub to slide axially relative to the spring holder along a limited range of movement defined between first and second axial positions, the connector spring biases the ferrule hub toward the first axial position, and the coupling between the ferrule hub and the spring holder provides a first positive stop that stops forward movement of the ferrule hub relative to the spring holder at the first axial position, the first positive stop provided by contact between one or more tabs on the ferrule hub and forward ends of one or more openings on the spring holder, and allowing the ferrule subassembly to be assembled with the connector spring pre-compressed to an initial compressed state prior to mounting the connector core within the connector body; and

wherein the plug body and the connector core are configured such that the connector spring is moved from the initial compressed state to a final compressed state when the connector core is loaded in the plug body.

2. The fiber optic connector of claim 1 , wherein the coupling between the ferrule hub and the spring holder provides a second positive stop that stops rearward movement of the ferrule hub relative to the spring holder at the second axial position.

3. The fiber optic connector of claim 2 , wherein the second positive stop is provided by contact between a front flange of the ferrule hub and a forward end of the spring holder.

4. The fiber optic connector of claim 1 , wherein the connector core interlocks with the plug body to retain the spring in the final compressed state.

5. A method for assembling a fiber optic connector, the fiber optic connector including a ferrule subassembly including a ferrule, a ferrule hub that attaches to the ferrule, a spring holder and a connector spring, the fiber optic connector including a plug body in which the ferrule subassembly mounts, the plug body having a plug end through which the ferrule extends when the ferrule subassembly is mounted within the plug body, the plug body defining a central longitudinal axis, the method comprising:

pre-assembling the ferrule subassembly such that the connector spring is pre-compressed in an initial compressed state between the ferrule hub and the spring holder;

coupling the spring holder to the ferrule hub to allow the ferrule and the ferrule hub to slide axially relative to the spring holder along a limited range of movement defined between first and second axial positions by using the connector spring to bias the ferrule hub toward the first axial position, and using the coupling between the ferrule hub and the spring holder to provide a first positive stop that stops forward movement of the ferrule hub relative to the spring holder at the first axial position, providing the first positive stop by contact between one or more tabs on the ferrule hub and forward ends of one or more openings on the spring holder;

loading the pre-assembled ferrule subassembly into the plug body and applying a secondary compression force to the connector spring as the pre-assembled ferrule assembly is loaded into the plug body to move the connector spring to a final compressed state; and

securing the ferrule subassembly in axial position relative to the plug body to retain the connector spring in the final compressed state.

6. The method of claim 5 , further comprising inserting the ferrule subassembly into a connector core, and mechanically interlocking the connector core with the plug body to secure the ferrule subassembly in axial position relative to the plug body.

7. The method of claim 6 , further comprising rotating the ferrule subassembly relative to the connector core to tune the fiber optic connector.

8. The method of claim 7 , further comprising splicing an optical fiber of a fiber optic cable to a stub optical fiber secured within the ferrule.

9. The method of claim 8 , further comprising assembling the fiber optic connector on a fixture, wherein the fixture includes a fixture spring for pulling back the fiber optic cable relative to the connector core.

10. The method of claim 9 , wherein the fixture spring has a spring force less than or equal to a spring force of the connector spring.

11. The method of claim 8 , further comprising tuning the fiber optic connector by rotationally orienting the ferrule at a desired rotational orientation prior to splicing the stub optical fiber to the optical fiber of the fiber optic cable.

12. The method of claim 8 , further comprising encasing the splice in an adhesive filled shell after splicing, the adhesive filled shell forming a part of the ferrule hub.

13. The method of claim 5 , further comprising using the coupling between the ferrule hub and the spring holder to provide a second positive stop that stops rearward movement of the ferrule hub relative to the spring holder at the second axial position.

14. The method of claim 13 , further comprising providing the second positive stop by contact between a front flange of the ferrule hub and a forward end of the spring holder.