Apparatus and method for optically transmitting electrical signals in the 20-300 gigahertz frequency range
First Claim
1. An apparatus for optically transmitting a narrow-band electrical signal having a frequency in the 20 to 300 GHz range, said apparatus comprising:
- a) a semiconductor laser with a lasing cavity having a length L for sustaining a laser beam, said lasing cavity having a round-trip distance defined by twice said length L, said round-trip distance corresponding to a round-trip resonance frequency;
b) a signal source for generating an electrical modulating signal having a modulation frequency contained in a narrow band, said narrow band comprising said round-trip resonance frequency;
c) an in-coupling means mounted on said semiconductor laser for delivering said electrical modulating signal to said semiconductor laser, thereby producing a sub-carrier modulated optical signal beam whose sub-carrier modulation frequency is comprised within a response band and corresponds approximately to said modulation frequency.
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Abstract
The invention discloses a method and an apparatus for optically transmitting a narrow-band optical signal beam having a sub-carrier frequency in the 20 to 300 GHz range. The apparatus has a semiconductor laser with a lasing cavity of length L. The length L preferably ranges from less than 1 mm to 10 mm, thereby defining the round-trip resonance frequency according to the following equation c/2 nL. The apparatus has a signal source for generating an electrical modulating signal having a modulation frequency contained in a narrow band containing the round-trip resonance frequency. An in-coupling means delivers the electrical modulating signal to the semiconductor laser which produces a sub-carrier modulated signal beam whose sub-carrier modulation frequency lies within a response band and corresponds to the modulation frequency. The apparatus further includes a biasing device for providing a biasing voltage for tuning the response band and the sub-carrier modulated signal beam. According to the method of the invention the biasing voltage is used to set the width of the response band and to set a phase shift in the sub-carrier modulated optical signal beam. Varying the biasing voltage thus allows to phase-modulate the sub-carrier modulated optical signal beam.
45 Citations
17 Claims
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1. An apparatus for optically transmitting a narrow-band electrical signal having a frequency in the 20 to 300 GHz range, said apparatus comprising:
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a) a semiconductor laser with a lasing cavity having a length L for sustaining a laser beam, said lasing cavity having a round-trip distance defined by twice said length L, said round-trip distance corresponding to a round-trip resonance frequency; b) a signal source for generating an electrical modulating signal having a modulation frequency contained in a narrow band, said narrow band comprising said round-trip resonance frequency; c) an in-coupling means mounted on said semiconductor laser for delivering said electrical modulating signal to said semiconductor laser, thereby producing a sub-carrier modulated optical signal beam whose sub-carrier modulation frequency is comprised within a response band and corresponds approximately to said modulation frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for optically transmitting a narrow-band electrical signal having a frequency in the 20 to 300 GHz range using a semiconductor laser with a lasing cavity, said method comprising the following steps:
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a) cleaving said semiconductor laser such that said lasing cavity has a length L, thereby setting a round-trip distance of said lasing cavity to twice said length L, said round-trip distance corresponding to a round-trip resonance frequency; b) generating an electrical modulating signal using a signal source, said electrical modulating signal having a modulation frequency contained in a narrow band, said narrow band comprising said round-trip resonance frequency; c) in-coupling said electrical modulating signal into said semiconductor laser using an in-coupling means mounted on said semiconductor laser, thereby producing a sub-carrier modulated optical signal beam whose sub-carrier modulation frequency is comprised within a response band and corresponds approximately to said modulation frequency. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification