Laser oscillating apparatus and method of driving laser beam source

• US 5,825,798 A
• Filed: 05/20/1996
• Issued: 10/20/1998
• Est. Priority Date: 05/19/1995
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Topcon
• Original Assignee: Kabushiki Kaisha Topcon
• Inventors: Ohishi, Masahiro, Koizumi, Hiroshi, Goto, Yoshiaki, Ohtomo, Fumio, Momiuchi, Masayuki
• Primary Examiner(s): Bovernick, Rodney B.
• Assistant Examiner(s): Wise, Robert E.
• Application Number:
  US08/650,730
• Time in Patent Office: 883 Days
• Field of Search: 372/22, 372/25, 372/75
• US Class Current: 372/75
• CPC Class Codes: H01S 3/09415 the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping
• CPC Class Codes: H01S 3/102 by controlling the active medium, e.g. by controlling the processes or apparatus for excitation H01S3/13 takes precedence
• CPC Class Codes: H01S 3/109 Frequency multiplication, e.g. harmonic generation
• CPC Class Codes: H01S 5/06216 Pulse modulation or generation

Abstract

The present invention relates to a laser oscillating apparatus using a semiconductor laser or the like and a method of driving a laser beam source. The present invention relates particularly to a laser oscillating apparatus or the like having a nonlinear optical medium for generating a second harmonic and capable of by-pulse driving a laser beam source with high efficiency. In the laser oscillating apparatus, a optical resonator is composed of at least a laser crystal and an output mirror. The nonlinear optical medium for generating the second harmonic is inserted into the optical resonator. The laser beam source can effect pumping on the optical resonator so that the period T of a drive pulse produced from a pulse driving means satisfies a relation in τ_FL >T-τ with respect to τ_FL (fluorescence lifetime). Further, a first pulse can drive the laser beam source with the degree of not leading to the emission of a laser beam and a second pulse can drive the laser beam source so that the laser beam source produces the laser beam.

Claims

1. A laser oscillating apparatus comprising:

an optical resonator comprising at least a laser crystal and an output mirror;

a laser beam source for pumping said optical resonator, said laser beam source having associated therewith a fluorescence lifetime τ

_FL ; and

pulse driving means for driving said laser beam source, said pulse driving means producing a series of pulses with a period T, each of said pulses having a pulse width of τ

;

wherein the fluorescence lifetime τ

_FL, the period T, and the pulse width τ

are related such that τ

_FL >

T-τ

.

2. The laser oscillating apparatus of claim 1, wherein each pulse of said series of pulses is of sufficient width to produce an emission of a laser beam from said laser beam source.

3. A laser oscillating apparatus comprising:

an optical resonator comprising at least a laser crystal and an output mirror;

a nonlinear optical medium inserted into said optical resonator, for generating a second harmonic;

a laser beam source for pumping said optical resonator, said laser beam source having associated therewith a fluorescence lifetime τ

_FL ; and

pulse driving means for driving said laser beam source, said pulse driving means producing a series of pulses with a period T, each of said pulses having a pulse width of τ

;

wherein the fluorescence lifetime τ

_FL, the period T, and the pulse width τ

are related such that τ

_FL >

T-τ

.

4. The laser oscillating apparatus of claim 3, wherein each pulse of said series of pulses is of sufficient width to produce an emission of a laser beam from said laser beam source.

5. A method of driving a laser beam source to activate the laser beam source for pumping an optical resonator composed of at least a laser crystal and an output mirror, said laser beam source having associated therewith a fluorescence lifetime τ

_FL, said method comprising driving said laser beam source with a series of pulses having a period T, each of said pulses having a pulse width of τ

;

wherein the fluorescence lifetime τ

_FL, the period T, and the pulse width τ

are related such that τ

_FL >

T-τ

.

6. The method of claim 5, wherein each pulse of said series of pulses is of sufficient width to produce an emission of a laser beam from said laser beam source.

7. A method of driving a laser beam source to activate the laser beam source for pumping an optical resonator including a nonlinear optical medium for generating a second harmonic and composed of at least a laser crystal and an output mirror, said laser beam source having associated therewith a fluorescence lifetime τ

_FL, said method comprising driving said laser beam source with a series of pulses having a period T, each of said pulses having a pulse width of τ

;

wherein the fluorescence lifetime τ

_FL, the period T, and the pulse width τ

are related such that τ

_FL >

T-τ

.

8. The method of claim 7, wherein each pulse of said series of pulses is of sufficient width to produce an emission of a laser beam from said laser beam source.

9. A laser oscillating apparatus comprising:

an optical resonator comprising at least a laser crystal and an output mirror;

a laser beam source for pumping said optical resonator, said laser beam source having associated therewith a fluorescence lifetime τ

_FL ; and

means for driving said laser beam source with a periodic series of pulses having a period T, each period of said periodic series of pulses comprising two or more pulses as a pulse set, said pulse set having a pulse set width τ

, said pulse set not producing the emission of a laser beam from said laser beam source until the last pulse of said pulse set;

wherein the fluorescence lifetime τ

_FL, the period T, and the pulse set width τ

are related such that τ

_FL >

T-τ

.

10. The laser oscillating apparatus of claim 9, further comprising a nonlinear optical medium inserted into said optical resonator, for generating a second harmonic.

11. A method of driving a laser beam source to activate the laser beam source for pumping an optical resonator composed of at least a laser crystal and an output mirror, said laser beam source having associated therewith a fluorescence lifetime τ

_FL, said method comprising driving said laser beam source with a periodic series of pulses having a period T, each period of said periodic series of pulses comprising two or more pulses as a pulse set, said pulse set having a pulse set width τ

, said pulse set not producing the emission of a laser beam from said laser beam source until the last pulse of said pulse set;

wherein the fluorescence lifetime τ

_FL, the period T, and the pulse width τ

are related such that τ

_FL >

T-τ

.

12. The method of claim 11, further including a nonlinear optical medium inserted into said optical resonator.