JPH11142686A - Ferrule and optical connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable anyone to easily connect optical fibers with simple tools even if working facilities are not disposed by having a ferrule substrate for previously fixing built-in fibers, cap members which are deposited in the rear half part of this ferrule substrate 11 and are provided with recessed parts with the outer edge of the ferrule substrate at the time of deposition and a holding member for holding the ferrule substrate and the cap members. SOLUTION: The ferrule substrate 11 is formed with fixing holes for the optical fibers in its front half part 11b. The upper half part of the rear half part 11c is opened and positioning grooves for positioning at least >=1 piece of the optical fibers are formed coaxially with the axial line of the fixing holes on the front surface of the rear half part 11c. The built-in fibers previously cut to mirror finished surfaces on the rear half part 11c side are fixed from the front ends of the fixing holes to part of the positioning grooves. The cap members 13, 14 are deposited on the rear half part 11c of the ferrule substrate 11 and are provided with notches for forming the recessed parts H with the outer edge of the ferrule substrate 11 at the time of deposition. The holding member 15 elastically holds the ferrule substrate 11 and the cap members 13, 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ferrule and an optical connector used for mechanically connecting optical fibers.

[0002]

2. Description of the Related Art To manufacture an optical connector used for mechanically connecting an optical fiber, an optical fiber core wire is bonded and fixed to a ferrule, and the connection end surface of the ferrule where the tip of the optical fiber is exposed is mirror-polished by a polishing machine. Is required.

[0003] For this reason, a polishing machine,
A special machine such as a heating machine for curing the adhesive is required.

[0004]

In recent years, with the widespread development of optical communication networks in general homes and the like, it has been required to assemble and process optical connectors at sites where optical fibers are laid. .

However, assembling an optical connector requires a high level of technical skill, and requires a plurality of tools and a large amount of time (about one hour per terminal of an optical fiber).
The present invention has been made in view of the above points, and an object of the present invention is to provide a ferrule and an optical connector in which anyone can easily connect an optical fiber with a simple tool without a processing facility. .

It is another object of the present invention to provide a ferrule and an optical connector which are easily assembled as described above, in which the connected optical fiber is hardly pulled out and high reliability is provided.

[0007]

According to the present invention, there is provided a ferrule having a first half portion and a second half portion, wherein a fixing hole for an optical fiber is formed in the front half portion, and The upper half of the section is open, and the upper half of the section is coaxial with the axis of the fixing hole, and at least one of the optical fibers is
A positioning groove for positioning more than one is formed, and a ferrule substrate to which a built-in fiber whose rear half portion has been mirror-cut in advance over a part of the positioning groove from the tip of the fixing hole is fixed, and a rear half portion of the ferrule substrate. Since the cover member is provided and provided with a notch that forms a recess between the outer edge of the ferrule substrate and the holding member that elastically holds the ferrule substrate and the cover member, is there.

According to another aspect of the present invention, there is provided an optical connector having a front half portion and a rear half portion, wherein the front half portion has an optical fiber fixing hole, and the rear half portion has an upper portion. A half is opened, and a positioning groove for positioning at least one or more optical fibers is formed on the upper surface of the rear half portion coaxially with the axis of the fixing hole. A ferrule substrate to which a built-in fiber whose rear half is mirror-cut is fixed, and a lid member which is attached to the rear half of the ferrule substrate and has a cutout which forms a concave portion between the ferrule substrate and an outer edge of the ferrule substrate when the ferrule substrate is attached. A ferrule having a holding member for elastically holding the ferrule substrate and the lid member, and a ferrule having a predetermined clearance between inner surfaces of the stop ring. Deposited on the stop ring and the stop ring is inserted through, it had a structure having a plug frame that holds the ferrule.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a ferrule and an optical connector according to the present invention will be described below in detail with reference to FIGS.

First, a ferrule 10 of the present invention is used by being incorporated into an optical connector 1 described later, and has a ferrule substrate 11, holding lids 13 and 14, and a spring pin 15 as shown in FIG.

As shown in FIGS. 2 and 3, the ferrule substrate 11 has a cylindrical body divided into a front half portion 11b and a rear half portion 11c by a flange portion 11a, and an optical fiber fixing hole 11d is provided at the center of the front half portion 11b. Are formed. The ferrule substrate 11 is formed in a semi-cylindrical shape in which the rear half 11c is open at the upper half. The rear half portion 11c is formed such that both side edges are stepped and the cross section in the low width direction is formed in a convex shape. A coating groove 11f for positioning is formed. The shape of the fiber groove 11e and the coating groove 11f is not particularly limited as long as the optical fiber can be positioned. For example, a V groove, a U groove, or the like is preferable. Also,
As shown in FIG. 2, the covering groove 11 f has a right end widened in the width direction and a guide surface 1 for guiding insertion of an optical fiber from outside.
1 g is formed. On the other hand, the front half 11b is slightly projected from the fixing hole 11d toward the fiber groove 11e, and the built-in fiber 12 is bonded and fixed in advance.

Here, the built-in fiber 12 is
The exposed portion from d to the first half 11b, which is the butting end surface, is mirror-polished, and the second half 11c is cut into a mirror surface, and a refractive index matching agent is applied in advance.

The holding lids 13 and 14 are connected to the ferrule substrate 11.
4A and 4B, a holding lid 13 shown in FIGS. 4A and 4B is used to fit an optical fiber connected to the built-in fiber 12 into a fiber groove 11e.
4 (c) and 4 (d), the cover 14 is provided with a coating groove 11f for coating the optical fiber connected to the built-in fiber 12.
Respectively. The holding lid 13 and the holding lid 14 are
Notches 13a and 14a are formed on the sides to form a concave portion H (see FIG. 1) between the outer edge of the ferrule substrate 11 when the ferrule substrate 11 is attached. Further, the holding lid 14 has a tapered guide surface 14b on one side (the right side in FIG. 4D) on which the optical fiber is inserted.

The spring pin 15 is connected to the ferrule substrate 1.
As shown in FIG. 5, this is a cylindrical pin that is assembled to the ferrule 10 while elastically holding the cover 1 and the holding lids 13 and 14.
A slit 15a is formed in the longitudinal direction.

The ferrule 10 configured as described above
Can be easily assembled as follows.

First, the holding lid 13 is arranged on the flange 11a side, and the holding lid 14 is arranged on the rear side of the holding lid 13, and fitted to the rear half 11c of the ferrule substrate 11. As a result, a recess H (see FIG. 1) is formed between the holding lids 13 and 14 and the outer edge of the ferrule substrate 11.

Next, the ferrule 10 shown in FIG. 1 can be assembled very easily by fitting the spring pin 15 into the ferrule substrate 11 from the rear half portion 11c where the holding lids 13 and 14 are fitted. In the ferrule 10 assembled in this manner, the ferrule substrate 11 and the holding lids 13 and 14 are elastically held by the spring force of the spring pin 15. At this time, the spring pin 15
Is fitted so as not to cover the concave portion H formed between the holding lids 13 and 14 and the outer edge of the ferrule substrate 11.

Therefore, for example, when an optical connector is manufactured at a site where an optical fiber is laid, the ferrule 10 is inserted into the ferrule substrate 11 from the rear half portion 11c side and easily protrudes from the built-in fiber 12. Can be connected together.

That is, when the optical fiber is inserted into the ferrule 10, the wedges W corresponding to the two concave portions H formed between the holding lids 13 and 14 and the outer edge of the ferrule substrate 11.
A wedge W is inserted into each concave portion H using a jig having the following.
For example, as shown in FIG. 6, in the case of a concave portion H formed between the holding lid 13 and the outer edge of the ferrule substrate 11, the wedge W
Is inserted into the recess H, and the wedge W expands the recess H against the spring force of the spring pin 15.

As a result, the ferrule 10 is mounted on the ferrule substrate 11 with the upper surface of the rear half 11c and the holding lids 13, 1
4 and a slight gap is formed. Due to this gap,
The ferrule 10 is a second half 11 c of the ferrule substrate 11.
The optical fiber FOP can be inserted from the side through the coating groove 11f and the fiber groove 11e.

Then, after the inserted optical fiber FOP is abutted against the built-in fiber 12, the wedge W is released from the concave portion H. Then, in the ferrule 10,
Due to the spring force of the spring pin 15, the holding lids 13, 1
4 presses the optical fiber FOP against the upper surface of the ferrule substrate 11.

As a result, the inserted optical fiber FOP is very easily optically connected to the built-in fiber 12 in a stable and low-loss state. Moreover, the ferrule 10 allows anyone to easily connect the optical fiber by using a simple tool such as the wedge without any special processing facility. Then, the connected optical fiber can be easily pulled out from the ferrule 10 by prying the recess H with the wedge W in the same manner as described above.

Here, the ferrule 10 has a rear half 11c.
In the case where the diameter of the outer circumference is small, as shown in FIG.
A semi-cylindrical auxiliary member 16 is arranged and a spring pin 15
Insert and assemble.

When an optical fiber is inserted into or pulled out of the ferrule 10 shown in FIG. 7, a wedge W is inserted into a concave portion H formed by the notch 13a of the holding cover 13 and the auxiliary member 16. In the same manner as described above, the optical fiber can be easily inserted and the internal fiber 12 can be inserted.
Can be connected or pulled out.

Next, the optical connector of the present invention is shown in FIGS.
The optical connector 1 is a ferrule 1
8, the ferrule 10, the stop ring 2, the spring 3, and the plug frame 4 as shown in FIG.
And the other components except the structure of the ferrule 10 correspond to the JIS C 5973 F04 type single core optical fiber connector.

The stop ring 2 is, as shown in FIG.
A cylindrical member having a slit 2a opened on the front edge side and a slit-shaped opening 2b formed substantially at the center in the longitudinal direction, and two circumferentially extending protrusions on the outer periphery adjacent to the slit 2a. 2c is provided. The stop ring 2 has a stepped portion 2d serving as a stopper for the spring 3 formed therein, and a knurled portion 2e provided on the outer periphery behind the stepped portion 2d.

The spring 3 has the shape shown in FIG.
It is manufactured based on the S standard and inserted into the stop ring 2. The spring 3 has a slit 2 a in the stop ring 2.
After the ferrule 10 is inserted from the side, the ferrule 10 is
When the ferrule 10 is inserted from the rear half 11c side, it is locked by the step 2d and urges the ferrule 10 toward the front slit 2a.

The plug frame 4 is a quadrangular prism-shaped member.
As shown in FIG. 11, a flange 11a of the ferrule substrate 11 is locked on the inner front side, a ridge 4a is formed so that a front half 11b protrudes forward, and a slit 4b is formed at a position corresponding to a slit at the rear. It is provided in. The plug frame 4 has slit-shaped locking holes 4 in the width direction on the upper and lower sides shown in FIG. 11 where the slits 4b are not formed.
c is formed.

The optical connector 1 configured as described above is
Assembled as shown in FIG.

That is, first, after the holding lid 13 and the holding lid 14 are fitted to the rear half 11c of the ferrule board 11 as described above, the spring pins 15 are fitted from the rear side.
The ferrule 10 shown in FIG. 1 is assembled.

Next, after the spring 3 is inserted into the stop ring 2 from the slit 2a side, the ferrule 10 is inserted from the rear half 11c side of the ferrule substrate 11.

Next, while pushing the ferrule 10 into the stop ring 2, the plug frame 4 is
Fit the stop ring 2 from the front side from the b side. Then, the plug frame 4 is fitted to the stop ring 2 in a state where the projections 2c are locked in the respective locking holes 4c, and the optical connector 1 is easily assembled.

Accordingly, the ferrule 10 is disposed between the ferrule substrate 11 and the stepped portion 2 d of the stop ring 2, with the flange 11 a of the ferrule substrate 11 being locked by the ridge 4 a of the plug frame 4 to restrict the protrusion forward. The optical connector 1 is held in a stable assembled state because it is urged toward the plug frame 4 by the spring 3.

At this time, when connecting the optical fiber to the assembled optical connector 1, as described above, the wedges are formed in the two concave portions H formed between the holding lids 13 and 14 of the ferrule 10 and the outer edge of the ferrule substrate 11. If the optical fiber is inserted using the small gap formed between the holding lids 13 and 14, the connection with the built-in fiber 12 can be made extremely easily. Also, when pulling out the optical fiber, pull out by the reverse operation,
The optical fiber can be easily pulled out from the optical connector 1.

Here, after assembling the optical connector 1, the time required until the pigtail type optical connector 1 to which the optical fiber was connected was measured. As a result, the assembly was easy within 2 minutes. Then, 100 pigtail type optical connectors 1 to which optical fibers were connected were prepared, and the connection loss and return loss of signal light transmitted from the outside were measured. The average was 0.3 dB or less and the average was 50 dB, respectively. It was confirmed that the above high characteristics were obtained, and characteristics not inferior to those of the conventional optical connector were obtained.

Also, since the ferrule 10 is always urged forward by the spring 3 with a predetermined urging force to the connection side, the optical connector 1 can be appropriately connected to another optical connector.

Here, the ferrule substrate 11 corresponds to FIG.
As shown in (a) and (b), a groove 11h may be formed at a position adjacent to the flange 11a on the upper surface of the rear half 11c. When the groove 11h is provided, when the axis of the fixing hole 11d and the axis of the fiber groove 11e do not coincide with each other, the built-in fiber 12 may break when inserted into the fixing hole 11d, or may cause bending loss due to extreme bending. Can be suppressed.

Further, like the ferrule 10 shown in FIG. 14, the holding cover 13 is formed so that both sides of the connection point C between the built-in fiber 12 and the inserted optical fiber FOP have the same length. When the presser lid 13 is formed in this manner,
When fitted on the ferrule substrate 11, the spring pin 15 is connected to the built-in fiber 12 and the inserted optical fiber FOP.
And the pressing force acts evenly from above.

Further, as shown in FIG. 15A, the holding lid 13 may be formed with a recess 13b at a position corresponding to the position of the ferrule substrate 11 adjacent to the flange 11a on the upper surface of the rear half 11c. By providing the concave portion 13b, the pressing lid 13 can reduce the pressing force acting on the built-in fiber 12, thereby suppressing an increase in bending loss due to bending of the built-in fiber 12. On the other hand, the holding lid 14 is
(B) As shown in FIG.
4b may be formed. When the holding lid 14 is formed with the concave portion 14b, the holding lid 14 relaxes the optical fiber FOP to be inserted after being assembled to the ferrule 10 or the optical connector 1 so as not to exert an excessive pressing force, and reduces the tensile strength of the inserted optical fiber FOP. Can be increased.

On the other hand, the ferrule substrate 11 and the holding lid 13,
The holding member for elastically holding the spring 14 may be, for example, a spring pin 15 formed in a cylindrical shape, a shape slightly crushed in the vertical direction like a spring pin 17 shown in FIG. As in the case of the spring pin 18 shown in (b), in addition to the slit 18a formed over the entire length in the longitudinal direction, a part of the slit 18b may be formed so as to realize an appropriate pressing force. . FIG.
As in the case of a spring pin 19 shown in FIG. 6 (c), it may be formed into a semi-cylindrical shape, and a ridge 19a may be provided at a position where it comes into contact with the outer surfaces of the ferrule substrate 11 and the holding lids 13, 14.

In the ferrule 10, when a tensile force acts on the optical fiber FOP in a direction in which the optical fiber FOP is pulled out while the optical fiber FOP is set, the optical fiber FOP and the built-in fiber 12 are separated from each other, and the optical connection is interrupted. May be done. In order to eliminate such inconveniences, it is desired that the ferrule 10 has a higher tensile resistance against the tensile force.

Here, since the tensile drag depends on the spring force of the spring pin 15, the tensile drag can be increased by increasing the spring force. However, if the spring force is excessively increased, the optical fiber FOP may be broken, or an excessive side pressure may be applied to the optical fiber due to deformation of the molded body, causing an increase in insertion loss.
Therefore, in order to reduce the load on the optical fiber FOP as much as possible even when a somewhat high spring force is applied, a measure is taken to clamp the coated portion of the optical fiber FOP. However, also in this case, a desired tensile resistance may not be obtained due to adhesion of silicone oil to the coating surface or a difference in Young's modulus of the coating material, and good optical connection may be hindered.

Therefore, in order to minimize the above problem, the spring force of the spring pin 15 is set to an appropriate range so that a desired tensile force can be obtained without increasing the insertion loss even if the optical fiber is directly held.

That is, according to the experiments by the present inventors, if the optical fiber FOP can withstand a tensile load of about 6 (N) when the optical fiber FOP is pulled, it is possible to suppress the occurrence of the interruption of the optical connection and obtain a good light It was confirmed that the connection could be maintained. Therefore,
The optical fiber FOP set in the ferrule 10 is 6
(N) Even if a tensile load of not less than 10 is applied, the ferrule 10
It is desirable not to be pulled out from That is, the ferrule 10 needs to have a tensile resistance of 6 (N) or more.

Therefore, it is preferable that the lower limit of the spring force of the spring pin 15 is set to a value that exhibits a tensile resistance that can withstand a tensile load of 6 (N). On the other hand, if the spring force of the spring pin 15 is excessively increased, the insertion loss due to the lateral pressure increases as described above. As an optical connector, if the insertion loss is 0.7 (dB) or less, it can sufficiently withstand actual use. Therefore, the upper limit of the spring force is such that the insertion loss due to the lateral pressure applied to the optical fiber FOP is 0.7 (d
It is preferable to set a value not exceeding B). More preferably, the upper limit of the spring force is set to a value such that the insertion loss due to the lateral pressure applied to the optical fiber FOP does not exceed 0.5 (dB).

Specifically, in the ferrule 10, when the optical fiber FOP is held by the ferrule substrate and the holding lid, the pressure applied to the optical fiber FOP is 39.2 (N / m).
m ² ), it is not possible to exhibit a tensile force that can withstand a tensile load of 6 (N), and conversely, 91.1 (N /
If it exceeds mm ² ), the insertion loss due to the lateral pressure applied to the optical fiber FOP will exceed 0.5 (dB). Therefore, it is preferable to set the spring force to a value such that the pressure applied to the optical fiber FOP is in the range of 39.2 to 91.1 (N / mm ² ).

Therefore, when setting the spring force by the spring pin 15, the diameter of the spring pin 15 shown in FIG. 6 and the dimension L (hereinafter referred to as the dimension between action points) shown in FIGS. L), and the spring force was adjusted by preparing various spring pins having different dimensions L between the action points. In other words, if the distance L between action points is short, the amount of deformation of the spring pin 15 when fitted to the ferrule 10 is large, and the spring force acting on the optical fiber FOP becomes strong. , The spring pin 15 when fitted to the ferrule 10
Since the amount of deformation of the optical fiber FOP decreases, the spring force acting on the optical fiber FOP decreases.

Here, for example, the ferrule substrate 11 having a diameter of 3.6 (mm) when assembled and the holding cover 1
3, 14, the dimension L between action points is 3.32 to 3.52 (m
Various types of spring pins 15 in the range of m) were prepared, and the ferrule 10 was assembled. And these ferrules 10
, A single mode fiber having an outer diameter of 125 (μm) was set. At this time, the range where the single mode fiber and the holding lids 13 and 14 were in contact was 4 (mm). If the contact range is less than 4 (mm), it is difficult to suppress the optical fiber with the holding lids 13 and 14, and it is difficult to effectively transmit the spring force of the spring pin 15 to the optical fiber. It is preferably at least 4 (mm).

Here, with respect to the various ferrules 10 assembled, an optical fiber pull-out test was performed, and the tensile drag was measured as shown in FIG. In addition, using various assembled ferrules, 1.55 (μ)
The signal light of m) was inserted, and the insertion loss was determined in the same manner as in the conventional method. The results are shown in FIG.
It was shown to.

As is apparent from FIG. 17, the insertion loss decreases as the dimension L between the action points increases, but it is about 3.49.
(Mm), the tensile drag becomes 6 (N) or less,
The optical fiber FOP is easily pulled out of the ferrule 10. Conversely, a tensile resistance of 6 (N) or more can be ensured up to a dimension L between action points of about 3.49 (mm), and it is difficult for the optical fiber FOP to be pulled out of the ferrule 10.
When the distance becomes about 3.35 (mm) or less, the insertion loss becomes 0.5 (d).
B) As described above, the characteristics of the ferrule, and thus the optical connector, are degraded.

Therefore, in the ferrule 10 of the present invention, it can be said that it is preferable to use a spring pin having a dimension L between action points in the range of 3.35 to 3.49 (mm).
Here, in the ferrule 10, the spring force is substantially reduced by employing the spring pin 15 having the dimension L between action points of 3.35 to 3.49 (mm).
A pressure of 39.2 to 91.1 (N / mm ² ) can be applied to the OP.

As described above, in the ferrule 10, by adjusting the spring force of the spring pin 15 as a holding member to an appropriate amount, the optical fiber is pulled out from the ferrule 10 while suppressing an increase in the insertion loss of the optical fiber. Can be effectively suppressed.

[0053]

According to the present invention, even if there is no processing facility,
A ferrule and an optical connector to which anyone can easily connect an optical fiber with a simple tool can be provided. Moreover, ferrules and optical connectors are easy to assemble, and compared to conventional ferrules and optical connectors,
The optical transmission characteristics are not inferior at all.

[Brief description of the drawings]

FIG. 1 is a front view of a ferrule of the present invention.

FIG. 2 is a plan view of a ferrule substrate constituting the ferrule of FIG. 1;

FIG. 3 is a sectional front view of the ferrule substrate of FIG. 2 cut along a longitudinal direction.

FIGS. 4A and 4B are side views (a) and (c) and plan views (b) and (d) of two types of lid members constituting the ferrule of FIG.

FIG. 5 is a perspective view of a holding member constituting the ferrule of FIG. 1;

FIG. 6 is a sectional view illustrating a procedure for inserting an optical fiber into the ferrule of FIG. 1;

FIG. 7 is a cross-sectional view showing a modification of the ferrule of FIG. 1 and illustrating a procedure for inserting an optical fiber.

FIG. 8 is a front view showing the optical connector of the present invention in a cross section of a lower half.

FIG. 9 is a front view showing a cross section of a lower half of the stop ring constituting the optical connector of FIG. 8;

FIG. 10 is a front view of a spring used in the optical connector of FIG. 8;

11 is a front view showing a cross section of a lower half of a plug frame constituting the optical connector of FIG. 8;

FIG. 12 is an exploded view for explaining an assembling procedure of the optical connector of FIG. 8;

FIG. 13 is a front view (a) and a plan view (b) showing a modified example of a ferrule substrate forming the ferrule and the optical connector of the present invention.

FIG. 14 is a front view showing a modified example of the lid member constituting the ferrule and the optical connector of the present invention, in which a rear half of the ferrule is sectioned.

FIG. 15 is a perspective view showing another modification of the lid member constituting the ferrule and the optical connector of the present invention.

FIG. 16 is a diagram showing a modified example of a holding member constituting the ferrule and the optical connector of the present invention.

FIG. 17 is a graph showing the relationship between the dimension between action points, tensile force, and insertion loss.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical connector 2 Stop ring 3 Spring 4 Plug frame 10 Ferrule 11 Ferrule board 11b First half 11c Second half 11d Fixing hole 11e Fiber groove (positioning groove) 12 Built-in fiber 13 Holding lid (lid member) 13a Notch 14 Holding lid (lid member) 14a Notch 15 Spring pin (holding member) FOP Optical fiber H Recess W Wedge

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeyuki Nakano 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd. (72) Inventor Takehiro Hayashi 2-6-1 Marunouchi, Chiyoda-ku, Tokyo No. Inside Furukawa Electric Co., Ltd. No. 2 Nippon Telegraph and Telephone Corporation

Claims (2)

[Claims] An optical fiber fixing hole is formed in the front half, an upper half of the rear half is open, and an axis of the fixing hole is formed on a rear half upper surface. A ferrule substrate on which a positioning groove for positioning at least one or more of the optical fibers is formed coaxially, and a built-in fiber whose rear half portion is mirror-cut in advance from the fixing hole tip to a part of the positioning groove is fixed. And a lid member attached to the rear half of the ferrule substrate and provided with a notch that forms a recess between the ferrule substrate and the outer edge of the ferrule substrate when the ferrule substrate is attached, and elastically holds the ferrule substrate and the lid member. A ferrule comprising a holding member. 2. An optical fiber fixing hole having a front half portion and a rear half portion, wherein the front half portion has an optical fiber fixing hole, and the rear half portion has an upper half opened, and the rear half portion upper surface has an axis line of the fixing hole. A ferrule substrate on which a positioning groove for positioning at least one optical fiber is formed coaxially and a built-in fiber whose rear half portion is mirror-cut in advance from the front end of the fixing hole to a part of the positioning groove is fixed; And a lid member attached to the rear half of the ferrule substrate and provided with a notch that forms a concave portion between the ferrule substrate and the outer edge of the ferrule substrate, and elastically holds the ferrule substrate and the lid member. A ferrule having a holding member, a stop ring for inserting the ferrule having a predetermined clearance between the inner surface of the stop ring via a spring, and the stop ring. An optical connector comprising a plug frame attached and holding the ferrule.