Oscillation mode switching laser devices

Claim 2

A laser device, comprising; a semiconductor laser, said semiconductor laser having at least two longitudinal modes with wavelengths λ 1 and λ 1 at which it is able to oscillate, and means for oscillating said semiconductor laser at the single longitudinal mode λ 0 ; and means for causing said semiconductor laser to oscillate in said longitudinal mode λ 1 without requiring a sustained external light input comprising input means for at least temporarily inputting to said semiconductor laser a wave of a wavelength which nearly coincides with said wavelength λ 1 of said semiconductor laser from λ 0 to λ 1 .

Claim 3

A laser device according to claim 1, including means for returning said semiconductor laser to its oscillating wavelength λ 0 from said wavelength λ 1 by inputting a wave with wavelength which nearly coincides with said wavelength λ 0 to said semiconductor laser.

Claim 4

A laser device according to claim 1, including means for returning said semiconductor laser to its oscillating wavelength 0 from said wavelength λ 1 by reducing a drive circuit of said semiconductor laser to near a threshold value.

Claim 5

A laser device according to claim 1, wherein said input is an optical switch means having a wave input section for receiving a first wave and a second wave and a clock input section for selecting an output wavelength from said first wave and said second wave.

Claim 6

A laser device according to claim 1, wherein said input means comprises a first wave source for producing a first wave, a second wave source and a connecting means to connect said first and second wave sources to said semiconductor laser, wherein one of said waves is selectively input to said semiconductor laser.

Claim 7

A laser device according to claim 5, wherein said connecting means is a beam splitter.

Claim 8

A laser device according to claim 5, wherein said connecting means is an optical wave guide.

Claim 9

A laser device accordinq to claim 1, wherein said input means is a laser source.

Claim 10

A laser device according to claim 1, wherein one of said longitudinal modes is at the Bragg wavelength, and the other one is a sub mode.

Claim 11

A laser device according to claim 1, wherein said semiconductor laser has an active layer and a grating means along the active layer.

Claim 12

A laser device according to claim 1, wherein said semiconductor laser is λ/4 shifted.

Claim 13

A laser device according to claim 1, wherein drive current of said laser is above a threshold value of said semiconductor laser.

Claim 14

A laser device according to claim 1, wherein said semiconductor laser has a drive current and a threshold value, said drive current of said laser being 1.4 times higher than the threshold value.

Claim 15

A laser device according to claim 1, further comprising: optical isolator means positioned between said semiconductor laser and said input means to selectively allow the wave to transfer from said input means to said semiconductor laser.

Claim 16

A laser device according to claim 1, wherein the transverse mode of said semiconductor lasers are the same.

Claim 17

A laser device according to claim 1, wherein the mode of said input wave and the modes of the output waves λ 0 , λ 1 of said semiconductor laser are transverse electric modes.

Claim 18

A laser device, comprising: a first semiconductor laser, said first semiconductor laser having at least two longitudinal modes with wavelengths λ 0 and λ 1 , respectively, both of which are able to oscillate, and means for causing said first semiconductor laser to oscillate at the single longitudinal mode λ 0 ; and means for causing said semiconductor laser to oscillate at the single longitudinal mode λ 1 without requiring a sustained external light input comprising a second semiconductor laser for at least temporarily inputting a laser wave which nearly coincides with said wavelength λ 1 to said first semiconductor laser to switch the oscillating single longitudinal mode of said first semiconductor laser from λ 0 to λ 1 , wherein said first semiconductor laser is operated with a wavelength bistability between said single longitudinal modes of λ 0 and λ 1 .

Claim 19

A laser device, comprising: a first semiconductor laser, said first semiconductor laser having at least two longitudinal modes with wavelengths λ 0 and λ 1 , respectively, both of which are able to oscillate, and means for causing said first semiconductor laser to oscillate at the single longitudinal mode λ 0 ; and means for causing said semiconductor laser to oscillate at the single longitudinal mode λ 1 without requiring a sustained external light input comprising a second semiconductor laser for at least temporarily inputting a laser wave which nearly coincides with said wavelength λ 1 to said first semiconductor laser to switch the oscillating single longitudinal mode of said first semiconductor laser from λ 0 to λ 1 , wherein said first semiconductor laser is operated with a wavelength bistability between said single longitudinal modes of λ 0 and λ 1 .

Claim 22

A method as claimed in claim 18, including eliminating said injected wave with the semiconductor laser continuing to oscillate in said second mode.

Claim 23

A method as claimed in claim 18, including returning said semiconductor laser to said first oscillating mode by injecting a wave having a wavelength close to that of said first mode.

Claim 24

A method as claimed in claim 20, including eliminating said injected wave with the semiconductor laser continuing to oscillate in said first mode.

Claim 25

A method as claimed in claim 18, including returning said semiconductor laser to said first mode by reducing a driving current to said semiconductor laser.

Claim 26

A method according to claim 18 wherein said altering step further comprises maintaining a driving current of said semiconductor laser above a predetermined value.

Claim 27

A laser device according to claim 17 wherein said causing means further comprises means for maintaining a driving current of said semiconductor laser above a predetermined value.

Claim 28

A laser device accordiing to claim 17 wherein said causing means further comprises means for maintaining a driving current of said semiconductor laser above a predetermined value.

Claim 29

A method according to claim 23 wherein said predetermined value is 1.4 times a threshold value for said semiconductor laser.

Claim 30

A laser device according to claim 24 wherein said predetermined value is 1.4 times a threshold value for said semiconductor laser.

Claim 31

A laser device according to claim 25 wherein said predetermined value is 1.4 times a threshold value for said semiconductor laser.