Method and apparatus to minimize effects of ase in optical measurements

A method for minimizing the effects of noise when measuring a response of a device under test to laser light comprising:

• scanning a source laser light through a range of lasing light wavelengths so as to produce source laser light with a time-varying lasing light wavelength;
• providing an interferometer with a first path with a first optical path length and a second path with a second optical path length, wherein there is a path length difference between the first optical path length and the second optical path length;
• splitting the source laser light into a first laser light portion and a second laser light portion, wherein the first laser light portion propagates through the first path and the second laser light portion propagates through the second path and there is a delay in propagation time between the first laser light portion and the second laser light portion due to the path length difference;
• combining the first laser light portion with the second laser light portion to produce a time-varying interference modulated test laser light and a time-varying interference modulated reference laser light;
• propagating the time-varying interference modulated test laser light to the device under test so as to cause the device under test to propagate responsive time-varying interference modulated test laser light;
• converting the responsive time-varying interference modulated test laser light to a responsive amplitude modulated electrical test signal;
• high pass filtering the responsive amplitude modulated electrical test signal;
• and
• processing the high pass filtered amplitude modulated electrical test signal so as to produce a time-varying electrical signal that represents the responsive time-varying interference modulated test laser light propagated by the device under test in response to the time varying interference modulated test laser light.

A method for minimizing the effects of noise when measuring a response of a device under test to laser light comprising:

• splitting a source laser light into a first light portion and a second laser light portion with a time-varying interferometer, whereby the first laser light portion and second laser light portion travel different optical path lengths;
• combining the first laser light portion with the second laser light portion to produce a time-varying interference modulated test laser light and a time-varying interference modulated reference laser light;
• propagating the time-varying interference modulated test laser light to the device under test to produce a responsive time-varying interference modulated test laser light;
• converting the responsive time-varying interference modulated test laser light to a responsive amplitude modulated electrical test signal;
• high pass filtering the responsive amplitude modulated electrical test signal;
• and
• processing the high pass filtered amplitude modulated electrical test signal to produce a time-varying electrical signal representing the responsive time-varying interference modulated test laser light propagated by the device under test in response to the time varying interference modulated test laser light.

A method for minimizing the effects of noise when measuring a response of a device under test to laser light comprising:

• providing source laser light at a lasing wavelength from a laser light source;
• modulating the phase or lasing wavelength so as to produce source laser light with a time-varying lasing light wavelength;
• imparting time-varying interference modulations to the source laser light to produce a time-varying interference modulated test laser light and a time-varying interference modulated reference laser light;
• propagating the time-varying interference modulated test laser light to the device under test so as to cause the device under test to propagate responsive time-varying interference modulated test laser light;
• converting the responsive time-varying interference modulated test laser light to a responsive amplitude modulated electrical test signal;
• high pass filtering the responsive amplitude modulated electrical test signal;
• and
• processing the high pass filtered amplitude modulated electrical test signal so as to produce a time-varying electrical signal that represents the responsive time-varying interference modulated test laser light propagated by the device under test in response to the time varying interference modulated test laser light.

A method for removing the effects of amplified spontaneous emission upon the response of a device under test to a lasing light comprising:

• propagating a high frequency time-varying lasing light to the device under test to cause the device under test to propagate responsive high frequency time-varying lasing light;
• converting the responsive high frequency time-varying lasing light to a responsive amplitude modulated electrical test signal;
• and
• high pass filtering the responsive amplitude modulated electrical test signal.

A system for minimizing the effects of noise when measuring a response of a device under test to laser light comprising:

• an interferometer for splitting a source laser light with a time-varying lasing light wavelength into a first laser light portion and a second laser light portion and combining the first laser light portion with the second laser light portion to produce a time-varying interference modulated test laser light and a time-varying interference modulated reference laser light;
• a device under test for receiving the test laser light, the device under test propagating a responsive time-varying interference modulated test laser light;
• a photodetector for converting the responsive time-varying interference modulated test laser light to a responsive amplitude modulated electrical test signal;
• a high pass filter for filtering the responsive amplitude modulated electrical test signal;
• and
• an modulation amplitude detector for processing the high pass filtered amplitude modulated electrical test signal so as to produce a time-varying electrical signal that represents the responsive time-varying interference modulated test laser light propagated by the device under test in response to the time varying interference modulated test laser light.

A system for minimizing the effects of noise when measuring a response of a device under test to laser light comprising:

• a time-varying interferometer for splitting a source laser light with a fixed lasing light wavelength into a first laser light portion and a second laser light portion and combining the first laser light portion with the second laser light portion to produce a time-varying interference modulated test laser light and a time-varying interference modulated reference laser light;
• a device under test for receiving the test laser light, the device under test propagating a responsive time-varying interference modulated test laser light;
• a photodetector for converting the responsive time-varying interference modulated test laser light to a responsive amplitude modulated electrical test signal;
• a high pass filter for filtering the responsive amplitude modulated electrical test signal;
• and
• an modulation amplitude detector for processing the high pass filtered amplitude modulated electrical test signal so as to produce a time-varying electrical signal that represents the responsive time-varying interference modulated test laser light propagated by the device under test in response to the time varying interference modulated test laser light.

A system for minimizing the effects of noise when measuring a response of a device under test to laser light comprising:

• a means for splitting a source laser light with a fixed lasing light wavelength into a first laser light portion and a second laser light portion and producing a time-varying interference modulated test laser light and time-varying interference modulated reference laser light;
• a device under test for receiving the test laser light, the device under test propagating a responsive time-varying interference modulated test laser light;
• a means for converting the responsive time-varying interference modulated test laser light to a responsive amplitude modulated electrical test signal;
• a means for filtering the responsive amplitude modulated electrical test signal;
• and
• a means for processing the high pass filtered amplitude modulated electrical test signal so as to produce a time-varying electrical signal that represents the responsive time-varying interference modulated test laser light propagated by the device under test in response to the time varying interference modulated test laser light.

A system for minimizing the effects of noise when measuring a response of a device under test to laser light comprising:

• a means for splitting a source laser light with a time-varying lasing light wavelength into a first laser light portion and a second laser light portion and producing a time-varying interference modulated test laser light and time-varying interference modulated reference laser light;
• a device under test for receiving the test laser light, the device under test propagating a responsive time-varying interference modulated test laser light;
• a means for converting the responsive time-varying interference modulated test laser light to a responsive amplitude modulated electrical test signal;
• a means for filtering the responsive amplitude modulated electrical test signal;
• and
• a means for processing the high pass filtered amplitude modulated electrical test signal so as to produce a time-varying electrical signal that represents the responsive time-varying interference modulated test laser light propagated by the device under test in response to the time varying interference modulated test laser light.