JPH06244487A - Device for coordinating laser beam time of laser device - Google Patents

Abstract

PURPOSE:To control the delay circuit of a light at the same time with the sweeping of the wavelength of a Ti sapphire laser so as to enable the mixing of light in each wavelength by branching a laser beam, and delaying it with an optical fiber and a prism so as to adjust a light path, and detecting the time difference, and feeding it back. CONSTITUTION:The beam of an exciting laser 1 is branched with a beam splitter 2, and a wavelength variable laser 3 is excited with one hand of the branched beams, and the beam of the wavelength variable laser 3 is incident on an optical 11. Furthermore, the other branched beam is incident on the optical mixer 11 through an optical fiber 4, a prism 5 on an X stage 7, and a prism 6. One part of the two beams which have entered the light mixer 11 is guided to a PIN photodiode 9 by a partial reflecting mirror 10, and the incidence timing of two beams is detected. An X stage controller 8 operates the stage 7 and adjusts the length of the light path of the other beam so that the incidence timings may accord with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser light time matching device for a laser device, and is applied to a laser device in which the oscillation wavelength range of the laser is widened by a light mixing method.

[0002]

2. Description of the Related Art A laser device is used as a light source for laser elemental analysis. In this laser device, the light mixing method is used as a method for expanding the oscillation wavelength range of the laser beam.

A conventional laser device using the light mixing method will be described with reference to FIGS. 3 and 4. The conventional apparatus shown in FIG. 3 has two pump lasers 01a and 01b, and a pulsed beam obtained by pumping the wavelength tunable laser 02 by the pump laser 01a and a pulsed beam of the pump laser 01b are The light is incident on the light mixer 3 by the mirrors M1 and M2. In this case, since the two beams are simultaneously incident on the light mixer 03, the pump lasers 01a and 01b are synchronized.

In the conventional device shown in FIG. 4, the pump laser 01
The pulsed beam of c is split by the beam splitter 04. Then, the tunable laser 05 is excited by one of the branched beams, and the other branched beam and the beam of the tunable laser 05 are guided to the optical mixer 03 by the mirrors M3, M4, and M5. In this case, since the two beams are simultaneously incident on the light mixer 03, the wavelength tunable laser 05 that does not have a time delay is used.

[0005]

After all, in the past, if a wavelength tunable laser with a time delay was used, two pump lasers would be required, which would increase the cost.

An example of a tunable laser is T_isapphire
I will give you a laser. T_iSapphire laser is about 700-9
Can oscillate in the wavelength range of 00 nm
By using the nonlinear effect of, the wavelength range from ultraviolet to near infrared is
It becomes possible to oscillate the enclosure. Excitation laser for light mixing
The YAG laser light used as the _i
The sapphire laser is emitted with a delay after being excited by the YAG laser.
Since it is shaken, there is a time difference here and mixing is not possible. See also T
_iThe sapphire laser, as shown in FIG.
Since the delay time differs depending on the length, in a simple optical delay circuit
Wavelength cannot be swept.

The present device solves this problem and controls the optical delay circuit at the same time as the wavelength sweeping of the T _i sapphire laser, thereby enabling light mixing at each wavelength.

[0008]

A laser beam branched from an excitation laser is delayed by an optical fiber and a prism. The optical fiber is fixed at time, and the prism is slid on the X stage to adjust the optical path length and correct the time difference due to the wavelength. A PIN photodiode is placed at a position where the beams coincide with each other on the optical path. With this, a time difference is detected and is fed back to the X stage for time matching. The PIN photodiode is an element that detects light, and the X stage is a stage that slides horizontally or vertically.

[0009]

The light mixing is to mix lights having two different frequencies in a substance, and is a method for generating lights having a sum frequency ω ₁ + ω ₂ and a difference frequency │ω ₁ -ω ₂ │. A non-linear crystal is used as the substance to be mixed, and this crystal needs to have no inversion symmetry. When one of the incident wavelengths is wavelength tunable, the generated light is also wavelength tunable, which expands the oscillation wavelength of the laser. However, the two incident laser beams must pass through the crystal at the same time, and this device is used for this time adjustment.

Using a T _i sapphire laser as a wavelength tunable laser, the wavelength generated by the optical mixing of the fundamental wave (700 to 900 nm) of the T _i sapphire laser with the fundamental wave of the YAG laser and the second harmonic wave, and T
Table 1 shows the wavelengths generated by light mixing when the second harmonic of the _i- sapphire laser is used.

[0011]

[Table 1]

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIG. As shown in the figure, pump laser 1 (YAG laser)
Beam from is split by the beam splitter 2,
One is a wavelength tunable laser ( _Ti sapphire laser) 3 via a mirror m1, and the other is an optical fiber 4 for light mixing.
Go to. A beam is emitted from the wavelength tunable laser 3 with a delay of several tens to several hundreds of nanoseconds, and a part thereof is directed to the PIN photodiode 9 by the mirrors m2, m3 and the partial reflection mirror 10.
Most of the light is incident on the light mixer 11. On the other hand, the optical fiber 4
After passing through the prisms 5 and 6 whose optical path length is variable on the X stage 7 which horizontally or vertically slides, a part of the beam is passed to the PIN photodiode 9 by the mirrors m4 and m5 and the partial reflection mirror 10. Mostly the light mixer 11
Incident on. The PIN photodiode 9 detects two beams, and the X stage controller 8
The X stage 7 is operated so that the two beams are incident at the same time at the position of the PIN photodiode 9.

[0013]

According to the present invention, a laser device whose wavelength range has been limited so far can oscillate in a wider region, and a laser capable of oscillating from ultraviolet to near infrared appears with one laser device.

FIG. 2 shows the delay time dependence of the wavelength of the T _i sapphire laser. Although this is analysis data, it may be corrected for several tens to several hundreds of nanoseconds.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between delay time and wavelength of a T _i sapphire laser.

FIG. 3 is a block diagram showing a conventional technique.

FIG. 4 is a block diagram showing a conventional technique.

[Explanation of symbols]

 1 Excitation Laser 2 Beam Splitter 3 Wavelength Tunable Laser 4 Optical Fiber 5, 6 Prism 7 X Stage 8 X Stage Controller 9 PIN Photodiode 10 Partial Reflection Mirror 11 Optical Mixer

Claims (1)

[Claims] 1. A beam of an excitation laser is branched, a wavelength tunable laser is excited by one of the branched beams, and the other beam branched from the beam of the wavelength tunable laser is incident on an optical mixer and mixed and output. In the laser device, a beam guide unit that guides the other branched beam and has a variable optical path length, a detection unit that detects the incident timing of the two beams that enter the optical mixer, and a detection unit that detects the beam And a controller for controlling the optical path length of the beam guide means so that the incident timings coincide with each other.