JPH07106676A - Optical waveguide type laser - Google Patents

Abstract

PURPOSE:To obtain a high intensity laser light having a single frequency from an optical waveguide type laser having an optical induction grating. CONSTITUTION:The optical waveguide type laser comprises an optical waveguide 11 added, at least partially, with rare earth ions and an optical induction grating type reflector 12 formed on a planar substrate. A dielectric multilayer reflector 13 is disposed on the input side of a laser resonator 10 and an optical waveguide type post-amplifier 14 added with rare earth ions is disposed on the output side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide type laser, and more particularly to a rare earth ion-doped glass optical waveguide type laser having a high utility value as a light source in the fields of optical communication, optical information processing, optical measurement and the like. It is a thing.

[0002]

2. Description of the Related Art A silica-based optical waveguide laser in which a rare earth ion such as erbium is added to a core is capable of obtaining an oscillation threshold of a low excitation light intensity and a high conversion efficiency by utilizing an optical confinement effect of a waveguide structure. Because it is possible and small,
Various applications are expected in fields such as optical communication, optical information processing, and optical measurement. Among other things, as an active ion,
The erbium ion-doped optical waveguide type laser has an extremely high utility value because it has an emission band in the 1.5 μm band, which is important for optical communication. Erbium ions are in the 0.82 μm band,
It has an absorption band in the near-infrared region such as the 0.98 μm band and the 1.48 μm band, and is excited by light of a wavelength suitable for these
Stimulated emission of light in the 1.5 μm band.

By constructing a rare earth-doped optical waveguide type laser resonator using a grating reflection mirror, the oscillation wavelength can be controlled by the grating period, and at the same time, the line width of the oscillation spectrum can be narrowed. Furthermore, by setting the waveguide length and the grating reflection band appropriately,
It is also possible to realize a single longitudinal mode optical waveguide type laser that oscillates at a single frequency. FIG. 2 shows the structure of a conventional optical waveguide type laser having a grating. This is described in the applicant's prior application (Japanese Patent Application No. 4-147).
298). In this optical waveguide type laser, an optical waveguide in which rare earth ions are added to a core 21 is used as an optical amplification medium, and a photoinduced grating waveguide 22 formed by irradiating writing light by a two-beam interference exposure method or a phase shift mask method is used. And the dielectric multilayer reflecting mirror is the other reflector 23. It is possible to control the reflection wavelength and the reflectance of the grating type reflector depending on the light-induced grating exposure condition.

When pumping light enters from one end facet of the optical waveguide of this optical waveguide type laser, erbium ions are excited. The fluorescence of the erbium ion in the resonator is reflected only at the wavelength that matches the grating reflection wavelength, laser oscillation starts when the gain exceeds the resonator loss, and laser oscillation light with a wavelength equal to the grating reflection wavelength is emitted from the other end face. Output.

[0005]

The conventional optical waveguide type laser has the following problems. The rare-earth-doped optical waveguide has a small excitation light absorption coefficient per unit length (980 nm absorption coefficient of the optical waveguide added with 0.5 wt% erbium ions: 0.5 dB / cm), so that a short resonator of 1 cm or less is used. In the case of a single-longitudinal-mode optical waveguide type laser that requires a long length, a small part of the excitation light is absorbed by the rare earth ions, and the rest is emitted from the output end without exciting the rare earth ions. The differential efficiency of light intensity was low. As a result, the conventional optical waveguide type laser such as the single longitudinal mode laser has a problem that the optical output is small. Therefore, development of a high-power optical waveguide type single longitudinal mode laser has been awaited.

Therefore, an object of the present invention is to provide a high-power optical waveguide type laser provided with an optically pumped grating.

[0007]

In order to solve the above-mentioned problems, the optical waveguide type laser of the present invention comprises an optical waveguide formed on a flat substrate and containing at least a portion of rare earth ions and photoinduced refraction. An optical waveguide type laser having a photo-induced grating type reflector formed by utilizing a rate change, characterized by having a rare earth ion-doped optical waveguide type post optical amplifier on the output side of a laser resonator.

[0008]

By arranging the rare earth ion-doped optical waveguide type post optical amplifier on the output side of the laser resonator, the weak single-mode laser oscillation light from the laser resonator is amplified by this post optical amplifier, and A laser output can be obtained. Further, since the photo-induced grating has a low loss at the pumping light wavelength, it is possible to efficiently pump the post optical amplifier by utilizing the transmitted pumping light that is not absorbed in the laser resonator.

[0009]

EXAMPLES The present invention will be described in detail below with reference to examples.

FIG. 1 shows an optical waveguide type laser according to the present invention. This optical waveguide type laser includes an optical waveguide type laser resonator 10. This optical waveguide type laser resonator 10 includes one optical waveguide (rare earth doped optical waveguide) 11 to which 0.1 to 2 wt% of rare earth ions are added, and a photo-induced grating type reflector 12 provided in a part thereof. , And a dielectric multilayer film reflection mirror 13 provided only on one end face of the optical waveguide. The distance (laser cavity length) between the photo-induced grating type reflector 12 and the dielectric multilayer film reflection mirror 13 is preferably as short as 1 cm or less in order to obtain single longitudinal mode laser oscillation. The rare earth ion-doped optical waveguide type post-optical amplification optical waveguide 14 that connects the photo-induced grating reflector 12 and the end face of the optical waveguide without the reflection mirror 13 has a length of several cm or more in order to obtain a high laser oscillation light output. It is desirable to have

Germanium added to the optical waveguide for forming the photo-induced grating has an absorption band in the ultraviolet region due to the defect, and the structure of the defect is changed by irradiating with light having a wavelength matching the absorption band, It causes a change in the refractive index of the optical waveguide. The amount of change in the refractive index is about 10 ⁻⁴ . In a germanium-doped optical waveguide, it is possible to increase the amount of change in refractive index by increasing the number of defects by hydrogen treatment under high temperature and high pressure.

(Example 1) A quartz optical waveguide doped with erbium and germanium was produced on a silicon substrate by a flame deposition method, and a grating was formed on a part of the optical waveguide by light irradiation. The amounts of erbium and germanium added to the buried optical waveguide described below were 1% by weight and 10% by weight, respectively. A dielectric multilayer film reflection mirror 13 (reflectance 99.9% at laser oscillation light wavelength 1535 nm, excitation light wavelength 9) is formed on one end surface of the optical waveguide.
After vapor deposition of a transmittance of 90% at 80 nm), an excimer laser (wavelength 245 nm, intensity 300 mJ) was used.
A photo-induced grating reflector 12 having a photo-induced grating having a length of 2 mm was formed using a phase shift mask. The reflection wavelength of this photo-induced grating reflector 12 was 1535 nm, the reflectance was 90%, and the reflection band was 0.1 nm or less. Further, the distance between the photo-induced grating and the dielectric multilayer film reflection mirror is 1 cm, and the length of the post optical amplifier 14 constituted by the curved optical waveguide is 19c.
m.

A laser oscillation experiment was performed by using a strained superlattice semiconductor laser light (output 100 mW) having a wavelength of 980 nm that matched the absorption band of erbium ions as excitation light, and injecting it from the end surface on which a dielectric multilayer film reflection mirror was deposited. It was As a result, it was revealed that the manufactured optical waveguide laser oscillates in a single longitudinal mode at 1535 nm which coincides with the grating reflection wavelength. The optical output of this optical waveguide type laser was as high as 1 mW.

(Comparative Example) The optical waveguide type laser manufactured in Example 1 was cut and removed to remove the rare earth ion-doped optical waveguide type post optical amplifier to obtain an optical waveguide type laser having a conventional structure.
When the laser oscillation characteristic was measured using the same pumping light source as in (1), the optical output was as small as 0.03 mW.

[0015]

As described above, by using the optical waveguide type laser of the present invention, it is possible to obtain laser light having a single frequency and high intensity.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing the structure of an optical waveguide type laser according to the present invention.

FIG. 2 is a schematic plan view showing the structure of a conventional optical waveguide type laser having a grating.

[Explanation of symbols]

 10 Laser Resonator 11 Rare-earth-doped Optical Waveguide 12 Photo-induced Grating Reflector 13 Dielectric Multilayer Reflector Mirror 14 Rare-earth Ion-doped Optical Waveguide Type Post-Optical Amplifier 21 Rare-earth Added Waveguide 22 Photo-induced Grating Reflector 23 Dielectric Multilayer Membrane reflection mirror

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number for FI Technical indication H01S 3/094 3/17 (72) Inventor Shoji Horiguchi 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] 1. An optical waveguide laser comprising a planar substrate and an optical waveguide at least a portion of which is doped with rare earth ions, and an optically induced grating reflector formed by utilizing an optically induced refractive index change. An optical waveguide type laser having a rare earth ion-doped optical waveguide type post optical amplifier on the output side of the laser resonator.