JPS6293622A - Apparatus for measuring semiconductive laser spectrum - Google Patents

Abstract

PURPOSE:To allow laser beam to be accurately incident to the end surface of the optical fiber connected to a beam spectrum analyzer, by performing the positional control of a lens on the basis of the output difference of a plurality of photodiodes to which laser beam is incident. CONSTITUTION:Laser beam emitted from a semiconductive laser device 1 passes through lenses 3, 4 and half mirrors 5, 6 to be condensed to the end surface of an optical fiber 2 and the spectrum thereof is measured by a beam spectrum analyzer 12. At this time, the laser beam reflected by the half mirror 6 is incident on a PIN photodiode 9. This photodiode 9 is divided into four sections and the difference signal of the respective output voltages of the divided photodiodes is applied to an automatic position controller 7 and the position of the lens 3 is adjusted so that a light emitting spot is positioned at the center of the photodiode 9. Further, by measuring the difference between the current values of four divided PIN photodiodes by an ammeter 11, the positional shift of a laser beam source can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for simultaneously measuring the spectrum of a semiconductor laser and the positional deviation of a light source.

[Prior art]

FIG. 4 is a schematic diagram of a conventional semiconductor laser spectrum measuring device, in which reference numeral 41 indicates a 14 conductor laser, and the semiconductor laser 41 is connected to an AI'C drive circuit .

Moreover, 43 and 44 are lenses for focusing the laser beam on the end face of the optical fiber 45. Then, as shown in FIG. 4, the laser beam is focused on the end surface of the optical fiber 45 by lenses 43 and 44, or the laser beam is directly incident on the end surface of an optical fiber (not shown) whose tip is processed into a lens. Then, the spectrum was measured by an optical spectrum analyzer 46 connected to an optical fiber 45.

Furthermore, based on the monitored value of the light emitted from the rear surface of the chip of the semiconductor laser 41 that is incident on the f'IN photodiode (not shown) attached to the semiconductor laser 41, the output of the semiconductor laser 41 is sent to the APC drive circuit 42. was controlled to be constant, and as a result, the amount of light incident on the end face of the optical fiber 45 was controlled.

Furthermore, FIG. 5 is a schematic diagram of a conventional positional deviation measuring device for a semiconductor laser light source, in which laser light from a semiconductor laser 51 passes through lenses 53 and 54.

Is it CI by the TV camera 52? The deviation from the projection setting center position was measured on T55.

[Problem that the invention seeks to solve]

In the conventional technology as described above, when laser light is focused onto the end face of an optical fiber using a lens, the focal position differs due to variations in the semiconductor laser, and the focal spot is skewed from the end face of the optical fiber, resulting in the coupling required for measurement being difficult. Sometimes I just couldn't get enough. Therefore, the XYZ with the semiconductor laser fixed
It is necessary to adjust the focal position by manually moving the stage 30 (see Figure 4) to finely adjust the relative position between the light source and the end face of the optical fiber, or by manually finely adjusting the position of the lens system. This has the disadvantage that the time required for this adjustment is wasted in the mass production selection process of semiconductor lasers. In addition, when measuring the positional deviation of a laser light source, there was a problem in that devices such as a TV camera and a CRT were bulky.

Furthermore, in the conventional technology, the amount of light incident on the end face of the optical fiber is controlled based on the output light monitor value from the rear face of the laser chip, so the amount of light emitted from the front face of the laser chip cannot be accurately controlled, and the amount of light incident on the end face of the fiber cannot be accurately controlled. The problem was that there were variations.

[Means for solving problems]

The present invention has been made in view of the above circumstances, and its purpose is to split a laser beam using a beam splinter and receive the light by a plurality of photodiodes, and output an output representing the light receiving position. The position of the lens is automatically controlled based on the value, and the positional deviation of the laser beam can be detected, eliminating the need for the manual fine-tuning of the position mentioned above, shortening the spectrum measurement time, and making it possible to measure the positional deviation of the light source. It is an object of the present invention to provide a conductor laser spectrum measuring device which can simultaneously carry out measurements and which can maintain a constant amount of light incident on the end face of an optical fiber depending on the implementation state.

A semiconductor laser spectrum measurement device according to the present invention is a laser spectrum measurement device that makes a semiconductor laser beam enter a lens (an end face of an optical fiber, and measures the spectrum of the laser beam with an optical spectrum analyzer connected to the optical fiber. ii. An automatic position control mechanism for moving the lens described in J in a direction perpendicular to the optical axis, a beam splitter provided between the lens and the optical fiber, and a beam splitter arranged to receive the laser beam split by the beam splitter. the automatic position control mechanism is operated based on the difference in the output value of each photodiode, and the optical axis of the lens is aligned with the optical axis of the semiconductor laser and the optical fiber. It is characterized in that it is further configured to measure the positional deviation of the laser light source based on the difference in the output value of each photodiode.

[Example] The present invention will be explained below based on drawings showing practical examples thereof. FIG. 1 is a schematic diagram of the apparatus of the present invention, in which 1 is a semiconductor laser, and 2 is an optical fiber with one end face facing the semiconductor laser 1 and the other end connected to an optical spectrum analyzer 12. ”〈There is a unit 16 between the conductor radar 1 and the optical fiber 2.
Lens 3 in order from conductor laser Iα. Lens 4. Half mirrors 5 and 6 are provided as beam splitters.

Semiconductor laser 1, lens 3. Lens 4. half mirror 5
, half mirror 6, and optical fiber 2 are arranged coaxially, and the laser light emitted from the semiconductor laser 1 is transmitted to the lens 3.
Lens 4. Pass through half mirror 5 and half mirror 6,
The light is made to enter the end face of the optical fiber 2. Further, the lens 3 can be moved in two force directions perpendicular to the optical axis and perpendicular to each other by the action of an automatic position control device 7, which will be described later.

In addition to the optical system described above, there are provided an output monitoring PIN photodiode 8 into which the laser beam reflected by the half mirror 5 is incident, and an rlN photodiode 9 into which the laser beam reflected by the half mirror 6 is incident. , the r'r
As shown in Fig. 2-3, the N7 diode 9 is divided into four parts with equal areas around the center, each having one area.
It functions as a diode. The 1'lN first diode 8 for output monitoring is connected to the PC drive circuit 10, and the PIN photodiode 8 for output monitoring is connected to the PC drive circuit 10.
The output is input to the PC drive circuit 10. Also PIN
The photodiode 9 is connected to the automatic position control device 7 and the ammeter 11, so that the output of the rrN7 metdiode 9 is input to the automatic position control device 7 and the ammeter 11. The ammeter 11 measures the output current of each of the four divided photodiodes.

Next, the operation of the device of the present invention will be explained. The laser beam emitted from the semiconductor laser 1 is transmitted through lens 3°, lens 4. The light passes through the half mirror 5 and the half mirror G and is focused on the end face of the optical fiber 2, and its spectrum is measured by the optical spectrum analyzer 12. The laser beam is split into three directions by half mirrors 5 and 6. Note that the splitting ratio in this case is always constant. The light reflected by the half mirror 15 is detected by the output monitor 1" IN photodiode 8, and the output of the output monitor rlN photodiode 8 is
The PC drive circuit 10 controls the output of the semiconductor laser 1 based on the output value of the PC drive circuit IO.

On the other hand, the light reflected by the half mirror 6 enters the PIN first diode 9 in the same manner as the incident state on the end face of the optical fiber 2.
incident on . Their positions are determined so that the center of the end face of the optical fiber 2 corresponds to the center of the first PIN diode 9. Figures 2 and 3 show the state of the light emitting spot of the laser beam incident on the PIN photodiode 9, and in the figure, a, b, c, and d are the four divided PIN photodiodes. represents. Here, 4 divided P
The output voltage of the IN photodiode is Va, Vb,
Assuming Vc and Vd, the light emitting spot in Figure 2 is I”
This represents the case where the laser light source is set to be located at the center of the IN photodiode 9, and Va+Vb=Vc+Vd.
, there is a relationship of Va+Vc=Vb+Vd. FIG. 3 shows a case where the light emitting spot is deviated from the center of the P■N photodiode 9, which indicates that the laser light source is deviated from the center position. In this case, Va + Vb and Vc
+Vd and Va +Vc+! :Vb +Vd
(In Figure 3, Va+Vb>Vc+Vd
, Va+Vc<Vb+Vd), the difference signal between the two is given to the automatic position control device 7, and the automatic position control device 7 adjusts the lens 3 so that the state of the light emitting diode becomes as shown in FIG.
Adjust the position. As a result, the laser beam is transferred to the optical fiber 2.
The light will be incident on the center of the end face.

In addition, the output of the PXN photodiode 9 is given to the ammeter 11, and since the difference in the current value of the four divided PIN photodiodes corresponds to the magnitude of the positional shift of the laser light source, the output of the PXN photodiode 9 is given to the ammeter 12. Misalignment can be measured.

In this example, the lens position control system is two-dimensional, but
It goes without saying that the same method can be used for the dimension ζ, and in this case, a plurality of PIN photodiodes 9 may be provided in the corresponding position control direction.

〔effect〕

As described in detail above, when using the apparatus of the present invention, the position of the lens is controlled based on the output difference of a plurality of photodiodes, so that the laser beam can be accurately incident on the end face of the optical fiber.

Similarly, based on the output difference of a plurality of first diodes, the positional deviation of the light source can be measured at the same time as the spectrum measurement. Further, in the above embodiment, since the laser output outside the semiconductor laser is monitored, the present invention has excellent advantages such as practical and accurate control and driving of the semiconductor laser output.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the device of the present invention, Figures 2 and 3 are PIN
A schematic diagram showing the shape of a light emitting spot on a photodiode,
FIG. 4 is a schematic diagram of a conventional spectrum measuring device, and FIG. 5 is a schematic diagram of a conventional positional deviation measuring device of a laser light source. 1... Semiconductor laser 2... Optical fiber 3.4.
...Lens 5.6...Half mirror 8...I"IN photodiode for output monitor 9...PIN photodiode

Claims (1)

[Claims] 1. A laser spectrum measuring device that makes a semiconductor laser beam enter an end face of an optical fiber through a lens, and measures the spectrum of the laser beam with an optical spectrum analyzer connected to the optical fiber, comprising: An automatic position control mechanism for moving in a direction perpendicular to the axis, a beam splitter provided between the lens and the optical fiber, and a plurality of photodiodes arranged to receive laser light split by the beam splitter. The automatic position control mechanism is operated based on the difference in output values of each photodiode to align the optical axis of the lens with the optical axes of the semiconductor laser and the optical fiber. Semiconductor laser spectrum measurement device. 2. In a laser spectrum measurement device that makes semiconductor laser light incident on the end face of an optical fiber through a lens and measures the spectrum of the laser light with an optical spectrum analyzer connected to the optical fiber, the lens is directed in a direction perpendicular to the optical axis. An automatic position control mechanism for moving, a beam splitter provided between the lens and the optical fiber, a plurality of photodiodes arranged to receive the laser light split by the beam splitter, and each photodiode. output detection means, and operates the position control mechanism based on the difference in output values of each photodiode to align the optical axis of the lens with the optical axis of the semiconductor laser and the optical fiber, and each 1. A semiconductor laser spectrum measuring device characterized in that the device is configured to measure a positional shift of a laser light source based on a difference in output values of photodiodes.