1. A system comprising:
a first I-Q modulator configured to modulate a first light source in response to first I and Q modulation signals;
a second I-Q modulator configured to modulate a second light source in response to second I and Q modulation signals;
a transmission signal processor configured to:
receive a data stream including data corresponding to a first data subchannel;
map said first data subchannel to a first optical transmission subchannel; and
output said first I and Q modulation signals to modulate said first light source to produce an optical transmission signal that includes wavelength components corresponding to said first optical transmission subchannel; and
a polarization multiplexer configured to receive outputs of said first and second I-Q modulators and output said optical transmission signal with first and second polarization modes.
2. The system of claim 1
wherein said transmission signal processor is further configured to:
map a second data subchannel of said data stream to a second optical transmission subchannel; and
output said second I and Q modulation signals to modulate said second light source to produce wavelength components of said optical transmission signal that correspond to said second optical transmission subchannel.
3. The system of claim 2, wherein said transmission signal processor is selectively configurable to implement different modulation protocols for said first and second transmission subchannels.
4. The system of claim 2, wherein a single laser provides both of said first and second light sources.
5. The system of claim 4, wherein said laser is a fixed-frequency optical source.
6. The system of claim 2, wherein said first data subchannel is mapped to a horizontal polarization of said optical transmission signal, and said second data subchannel is mapped to a vertical polarization of said optical transmission signal.
7. The system of claim 2, further comprising an optical receiver including an optical hybrid configured to recover I and Q signals for each of said first and second polarization modes.
8. The system of claim 2, further comprising a first optical receiver configured to recover said first data subchannel from said optical transmission signal, and a second optical receiver configured to recover said second data subchannel from said optical transmission signal.
9. The system of claim 1, further comprising an optical receiver configured to recover data corresponding to said first data subchannel from said first optical transmission subchannel.
10. The system of claim 9, wherein said optical receiver is configured to recover data from fewer than all optical transmission subchannels present on said optical transmission signal.
11. The system of claim 1, further comprising digital to analog converters configured to convert said first I and Q modulation signals to analog signals output to said first I-Q modulator.
12. A method comprising:
configuring a first I-Q modulator to modulate a first light source in response to first I and Q modulation signals and a second I-Q modulator to modulate a second light source in response to second I and Q modulation signals; and
configuring a transmission signal processor to:
receive a data stream including data corresponding to first and second data subchannels;
map said first and second data subchannels to first and second optical transmission subchannels; and
output said first and second I and Q modulation signals to modulate said first and second light sources to produce an optical transmission signal that includes wavelength components corresponding to said first and second optical transmission subchannels.
13. The method of claim 12 further comprising:
configuring a polarization multiplexer to receive outputs of said first and second I-Q modulators and output said optical transmission signal with first and second polarization modes.
14. The method of claim 13, wherein said transmission signal processor is selectively configurable to implement different modulation protocols for said first and second transmission subchannels.
15. The method of claim 13, wherein a single laser provides both of said first and second light sources.
16. The method of claim 13, wherein said first data subchannel is mapped to a horizontal polarization of said optical transmission signal, and said second data subchannel is mapped to a vertical polarization of said optical transmission signal.
17. The method of claim 13, further comprising configuring an optical receiver including an optical hybrid to recover I and Q signals for each of said first and second polarization modes.
18. The method of claim 13, further comprising configuring a first optical receiver to recover said first data subchannel from said optical transmission signal, and configuring a second optical receiver to recover said second data subchannel from said optical transmission signal.
19. The method of claim 12, further comprising configuring an optical receiver to recover data corresponding to said first data subchannel from said first optical transmission subchannel.
20. The method of claim 19, wherein said optical receiver is configured to recover data from fewer than all optical transmission subchannels present on said optical transmission signal.
21. The method of claim 12, further comprising configuring digital to analog converters to convert said first I and Q modulation signals to analog signals output to said first I-Q modulator.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An optical pickup for recording information on an optical recording medium and retrieving information from the optical recording medium by radiating a light beam on the optical recording medium comprising:
a light source which emits the light beam;
an object lens which converges the tight beam into a convergent light beam and directs the convergent light beam to a recording layer of the optical recording medium; and
an aberration correction lens assembly between the light source and the object lens and including at least one movable lens which is movable in an optical axis direction, the aberration correction lens assembly controlling the movable lens to convert the light beam to one of a convergent light beam and a divergent light beam so as to correct spherical aberration, wherein a distance between a principal plane of the aberration correction lens assembly on a light emergent side and a principal plane of the object lens on a light incident side falls within a range determined in accordance with a numerical aperture of the object lens, a focal length of the aberration correction lens assembly on the light emergent side, and a focal length of the object lens,
wherein the distance between the principal plane of the aberration correction lens
assembly on the light emergent side and the principal plane of the object lens is determined by the following equation:
(
f
2
+
f
3
)
–
10
\u2062
f
3
2
\u2061
(
mm
)
–
1
3
\u2062
N
\u2062
\u2062
A
4
<
e
2
<
(
f
2
+
f
3
)
+
10
\u2062
f
3
2
\u2061
(
mm
)
–
1
3
\u2062
N
\u2062
\u2062
A
4
where e2 represents the distance between the principal plane of a lens in the aberration correction lens assembly on the most light emergent side and the principal plane of the object lens, NA represents the numerical aperture of the object lens, f2 represents the focal length of the aberration correction lens assembly on the light emergent side, and f3 represents the focal length of the object lens,
wherein the numerical aperture of the object lens is not less than 0.80, and
wherein the focal length of the object lens is not greater than 2 mm.
2. The optical pickup according to claim 1, wherein the aberration correction lens assembly includes a positive lens group and a negative lens group, the movable lens included in at least one of the positive and negative lens groups, and a distance between a principal plane of the positive lens group and a principal plane of the negative lens group along the optical axis direction being changeable by the movable lens.
3. The optical pickup according to claim 2, wherein the aberration correction lens assembly comprises an expander lens assembly.
4. The optical pickup according to claim 1, wherein the movable lens comprises a collimator lens which converts the light beam emitted from the light source into a generally parallel light beam.
5. An optical pickup for recording information on a recording medium and retrieving information from the recording medium by radiating a light beam on the recording medium, comprising:
first lens means for directing a convergent light beam to a recording layer of the recording medium; and
second lens means located between a light source and the first lens means and including at least one movable lens such that the movable lens converts the light beam to one of a convergent light beam and a divergent light beam so as to correct spherical aberration,
wherein a distance between a principal plane of the second lens means on a light emergent side and a principal plane of the first lens means on a light incident side falls within a range determined in accordance with a numerical aperture of the first lens means, a focal length of the second lens means on the light emergent side, and a focal length of the first lens means,
wherein the distance between the principal plane of the second lens means on the light emergent side and the principal plane of the first lens means on the light incident side is determined by the following equation:
(
f
2
+
f
3
)
–
10
\u2062
f
3
2
\u2061
(
mm
)
–
1
3
\u2062
N
\u2062
\u2062
A
4
<
e
2
<
(
f
2
+
f
3
)
+
10
\u2062
f
3
2
\u2061
(
mm
)
–
1
3
\u2062
N
\u2062
\u2062
A
4
where e2 represents the distance between the principal plane of the second lens means on the light emergent side and the principal plane of the first lens means, NA represents the numerical aperture of the first lens means, f2 represents the focal length of the second lens means on the light emergent side, and f3 represents the focal length of the first lens means,
wherein the numerical aperture of the first lens means is not less than 0.80, and
wherein the focal length of the first lens means is not greater than 2 mm.
6. The optical pickup according to claim 5, wherein the second lens means includes a positive lens group and a negative lens group, the movable lens included in at least one of the positive and negative lens groups, and a distance between a principal plane of the positive lens group and a principal plane of the negative lens group along an optical axis direction being changeable by the movable lens.
7. The optical pickup according to claim 6, wherein the second lens means comprises an expander lens assembly.
8. The optical pickup according to claim 5, wherein the movable lens comprises a collimator lens which converts the light beam emitted from the light source into a generally parallel light beam.
9. An optical pickup for recording information on a recording medium and retrieving information from the recording medium by radiating a light beam on the recording medium comprising:
a light source which emits the light beam;
an object lens which converges the light beam into a convergent light beam and directs the convergent light beam to the recording medium;
a collimator lens located between the light source and the object lens; and
a mechanism for moving at least one of the light source and the collimator lens to convert the light beam, incident on the object lens, to one of a convergent light beam and a divergent light beam so as to correct spherical aberration,
wherein a distance between a principal plane of the collimator lens on a light emergent side and a principal plane of the object lens on a light incident side falls within a range determined in accordance with a numerical aperture of the object lens, a focal length of the collimator lens on the light emergent side, and a focal length of the object lens,
wherein the distance between the principal plane of the collimator lens on the light emergent side and the principal plane of the object lens on the light incident side is determined by the following equation:
(
f
2
+
f
3
)
–
10
\u2062
f
3
2
\u2061
(
mm
)
–
1
3
\u2062
N
\u2062
\u2062
A
4
<
e
2
<
(
f
2
+
f
3
)
+
10
\u2062
f
3
2
\u2061
(
mm
)
–
1
3
\u2062
N
\u2062
\u2062
A
4
where e2 represents the distance between the principal plane of the collimator lens on the light emergent side and the principal plane of the object lens, NA represents the numerical aperture of the object lens, f2 represents the focal length of the collimator lens on the light emergent side, and f3 represents the focal length of the object lens,
wherein the numerical aperture of the object lens is not less than 0.80, and
wherein the focal length of the object lens is not greater than 2 mm.
10. The optical pickup according to claim 9, wherein the collimator lens converts the light beam emitted from the light source into a generally parallel light beam.