Semiconductor laser apparatus

Details Semiconductor laser apparatus Semiconductor laser apparatus

2000-09-07

2004-02-17

Ip, Paul (Department: 2828)

Coherent light generators

Particular pumping means

Pumping with optical or radiant energy

C372S070000, C372S071000

Reexamination Certificate

active

06693941

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a semiconductor laser apparatus. This invention particularly relates to a surface emission type of semiconductor laser apparatus, in which a semiconductor laser device is employed as a pumping beam source.
2. Description of the Related Art
With the rapid advances made in functions and performance of optical information processing apparatuses, image processing apparatuses, printing apparatuses, and the like, in recent years, there has arisen a strong demand for semiconductor laser devices having high output power and capable of producing laser beams of high quality.
As a short-wavelength semiconductor laser device, which produces a laser beam having a wavelength of a 410 nm band, there has heretofore been proposed a semiconductor laser device comprising a GaN substrate, an n-GaN buffer layer, an n-InGaN anti-cracking layer, an AlGaN
-GaN modulation-doped superlattice cladding layer, an n-GaN optical waveguide layer, an undoped InGaN
-InGaN multiple quantum well active layer, a p-AlGaN carrier blocking layer, a p-GaN optical waveguide layer, an AlGaN/p-GaN modulation-doped superlattice cladding layer, and a p-GaN contact layer, which layers are formed on the GaN substrate. The GaN substrate is obtained by forming GaN on a sapphire substrate, growing GaN by the utilization of selective growth and by use of SiO
2
as a mask, and thereafter separating the sapphire substrate. Such a semiconductor laser device is reported in, for example, “Jpn. J. Appl. Phys.,” vol. 37, pp. L1020, 1998. However, with the proposed semiconductor laser device, wherein a stripe width is as narrow as 2 &mgr;m, only an optical output power of as low as 100 mW can be obtained.
As for a semiconductor laser device for producing a red laser beam, it has been reported in, for example, “IEEE Photonics Technology Letters,” Vol. 11, pp. 791, 1999, that a single-mode semiconductor laser, which produces a laser beam having a wavelength of 660 nm with an output power of 400 mW, has been achieved. However, the reported semiconductor laser device has the problems in that a side lobe arises in a transverse mode, and good beam characteristics cannot be obtained. Also, though the reported semiconductor laser device has a broad area structure, the reported semiconductor laser device has the problems in that, since the end face optical density is high, it is difficult for the output power to be enhanced even further, and the reliability with the passage of time is low. As for single-stripe semiconductor laser devices for producing a red laser beam, attempts have heretofore been made to employ a window structure for enhancing the output power and accomplishing oscillation in a fundamental mode. However, currently, with the single-stripe semiconductor laser devices for producing a red laser beam, which have the window structure, the output power is practically limited to approximately 50 mW.
Different examples of techniques for enhancing the output power include semiconductor laser pumped second-harmonic-generation (SHG) solid lasers. However, the semiconductor laser pumped SHG solid lasers have the problems in that, since the life of the fluorescence produced by the rare earth element of the laser crystal is markedly long, it is difficult for the laser beam produced by the solid laser to be modulated quickly with direct modulation of the pumping semiconductor laser. Also, the semiconductor laser pumped SHG solid lasers have the problems in that, since the second harmonic is utilized, the efficiency cannot be kept high.
As a laser device having a high output power and undergoing oscillation in a fundamental transverse mode, a semiconductor laser pumped, surface emission type of laser device, in which an AlGaAs type of semiconductor is employed, is described in, for example, U.S. Pat. No. 5,627,853. However, in U.S. Pat. No. 5,627,853, as for a technique for producing a laser beam having a wavelength shortened even further, it is described only that the SHG is utilized. In U.S. Pat. No. 5,627,853, nothing is described about a surface emission type of laser device, which produces a laser beam having a short wavelength with a high efficiency and in which the SHG is not utilized.
As lasers for producing a laser beam having a wavelength of an ultraviolet region, solid lasers, which produces a laser beam having a wavelength shorter than 400 nm and utilizes third harmonic generation (THG) driven in a pulsed mode, have heretofore been used in practice. However, the solid lasers utilizing the THG have the problems in that the efficiency cannot be kept high in producing a continuous wave (CW) with the THG, and therefore the solid lasers are not practical. Also, in order for the oscillation in the CW mode of the THG to be achieved at a high efficiency, the second harmonic of the fundamental wave must be resonated. In such cases, the temperature of the resonator must be controlled at a markedly high accuracy of within 0.01° C. The strict control requirement also makes the solid lasers utilizing the THG unpractical. Further, as a different technique for producing a laser beam having a wavelength of the ultraviolet region, it may be considered to obtain an ultraviolet laser beam having a wavelength shorter than 400 nm with the generation of the second harmonic of a beam produced by a Cr:LiSAF or Cr:LiCAF crystal. However, in such cases, since re-absorption of the beam produced by the Cr:LiSAF or Cr:LiCAF crystal occurs, it is difficult for a beam having a wavelength falling within the range of 700 nm to 800 nm to be produced efficiently.
Also in U.S. Pat. No. 5,627,853, nothing is described about a laser device for producing a laser beam having a wavelength of the ultraviolet region.
As described above, with the conventional semiconductor laser devices for producing a laser beam having a wavelength of the red region, it is difficult for a high output power and oscillation in the fundamental mode to be obtained.
Also, as for the laser devices for producing a laser beam having a wavelength of the ultraviolet region, a high-efficiency wavelength converting laser, in which a surface emission laser is utilized and the SHG of the ultraviolet region is utilized, has not been proposed in the past.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a semiconductor laser apparatus, which produces a laser beam having a wavelength of a red region, and which undergoes oscillation in a fundamental mode with a high reliability and a high efficiency and up to a high output power.
Another object of the present invention is to provide a semiconductor laser apparatus, which produces a laser beam having a wavelength of an ultraviolet region, and which undergoes oscillation in a fundamental mode with a high reliability and a high efficiency and up to a high output power.
The present invention provides a first semiconductor laser apparatus, comprising:
i) a pumping beam source constituted of a semiconductor laser device, in which a composition selected from the group consisting of InGaN and GaN is employed in an active layer, and
ii) a surface emission type of semiconductor device comprising:
a) a substrate, and
b) an active layer, which is constituted of a composition selected from the group consisting of InGaAlP and InGaP and is provided on the substrate,
the surface emission type of semiconductor device being pumped by the pumping beam source to produce a laser beam.
InGaN generally means compounds represented by In
X
Ga
1−X
N (where 0<X<1).
The present invention also provides a second semiconductor laser apparatus, comprising:
i) a pumping beam source constituted of a semiconductor laser device, in which a composition selected from the group consisting of InGaN and GaN is employed in an active layer, and
ii) a surface emission type of semiconductor device comprising:
a) a substrate,
b) a semiconductor layer, which is overlaid on the substrate and contains an active layer constituted of a composition selected from the group consistin

Affiliated with

Also associated with

Rating

Semiconductor laser apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Semiconductor laser apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor laser apparatus will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3354974