Interferometric wavemeter for broadband sensors in photonic systems
Disclosed herein are embodiments of a broadband wavemeter system comprising: a laser source to generate an optical signal having one or more wavelengths; a tap to separate a portion of the optical signal from the laser source; a splitter to split an incoming optical signal from the tap into a plurality of outgoing optical signals; a plurality of wavemeters, each one in the plurality to receive one of the outgoing optical signals from the splitter, in which each wavemeter in the plurality of wavemeters comprises a Mach-Zehnder Interferometer (MZI), and each wavemeter has at least one of free spectral range (FSR) detuning and center wavelength detuning, and a control circuit to collate outputs from individual ones of the plurality of wavemeters to monitor, detect and control the laser source.
1 . A photonic integrated circuit, comprising:
a tap to bifurcate a portion of an optical signal from a laser source, the optical signal having one or more wavelengths;
a splitter to split the bifurcated portion of the optical signal from the tap into a plurality of outgoing optical signals;
a plurality of wavemeters coupled to the splitter in parallel, each one in the plurality to receive one of the outgoing optical signals from the splitter; and
a control circuit to collate outputs from individual ones of the plurality of wavemeters, wherein:
each wavemeter in the plurality of wavemeters comprises
a Mach-Zehnder Interferometer (MZI),
the MZI in each wavemeter comprises two arms having an arm length difference between the two arms,
different wavemeters in the plurality of wavemeters have different arm length differences,
a first wavemeter of the plurality of wavemeters has a first free spectral range (FSR 1 ),
a second wavemeter of the plurality of wavemeters has a second free spectral range (FSR 2 ),
FSR 2 =FSR 1 +m/n *FSR 1 or FSR 2 =FSR 1 −m/n *FSR 1 ,
m is an integer other than zero, and
n is equal to or smaller than a total number of wavemeters in the plurality of wavemeters.
2 . The photonic integrated circuit of claim 1 , wherein different wavemeters in the plurality of wavemeters have different free spectral ranges.
3 . The photonic integrated circuit of claim 1 , wherein:
each wavemeter in the plurality of wavemeters further includes a photodetector at an output of the MZI, and
the photodetector is to measure a wavelength corresponding to a slope of optical power intensity at a quadrature point from peak intensity of the one of the outgoing optical signals from the splitter at the output of the MZI.
4 . The photonic integrated circuit of claim 3 , wherein:
the slope is a measure of sensitivity of a wavemeter.
5 . The photonic integrated circuit of claim 1 , wherein the laser source is a broadband laser source to generate optical signals having wavelengths between 700 nm and 2500 nm.
6 . The photonic integrated circuit of claim 1 , wherein the plurality of wavemeters includes a phase calibration wavemeter.
7 . The photonic integrated circuit of claim 1 , wherein the plurality of wavemeters includes a loss calibration port.
8 . An interferometric wavemeter system, comprising:
a broadband laser source to generate an optical signal having one or more wavelengths;
a tap to bifurcate a portion of the optical signal from the broadband laser source;
a splitter to split the bifurcated portion of the optical signal from the tap into a plurality of outgoing optical signals;
a plurality of wavemeters coupled to the splitter in parallel, each one in the plurality to receive one of the outgoing optical signals from the splitter; and
a control circuit to collate outputs from individual ones of the plurality of wavemeters to control the broadband laser source, wherein:
the plurality of wavemeters is configured for central wavelength detuning, and
each wavemeter in the plurality of wavemeters comprises:
a Mach-Zehnder Interferometer (MZI); and
a photodetector at an output of the MZI.
9 . The interferometric wavemeter system of claim 8 , wherein:
the MZI in each wavemeter comprises two arms having an arm length difference between the two arms.
10 . The interferometric wavemeter system of claim 9 , wherein: different wavemeters have similar arm length differences.
11 . The interferometric wavemeter system of claim 8 , wherein the photodetector is to measure a wavelength at peak intensity of an optical signal at the output.
12 . The interferometric wavemeter system of claim 8 , wherein a center wavelength of any one wavemeter is different from another center wavelength of any other wavemeter.
13 . The interferometric wavemeter system of claim 8 , wherein: a center wavelength of any one wavemeter of the plurality of wavemeters differs from a first center wavelength of a first wavemeter of the plurality of wavemeters by an integer fraction of a difference between the first center wavelength and a second center wavelength of a second wavemeter of the plurality of wavemeters.
14 . The interferometric wavemeter system of claim 8 , wherein the plurality of wavemeters includes a phase calibration wavemeter.
15 . The interferometric wavemeter system of claim 8 , wherein the plurality of wavemeters includes a loss calibration port.
16 . A photonic integrated circuit, comprising:
a tap to bifurcate a portion of an optical signal;
a splitter to split the bifurcated portion of the optical signal from the tap into a plurality of outgoing optical signals;
a plurality of wavemeters coupled to the splitter in parallel, each one in the plurality to receive one of the outgoing optical signals from the splitter; and
a control circuit to collate outputs from individual ones of the plurality of wavemeters, wherein:
each wavemeter in the plurality of wavemeters comprises a Mach-Zehnder Interferometer (MZI),
the MZI in each wavemeter comprises two arms having an arm length difference between the two arms,
different wavemeters in the plurality of wavemeters have approximately equal arm length differences, and
different wavemeters in the plurality of wavemeters have different center wavelengths.
17 . The photonic integrated circuit of claim 16 , wherein:
a first wavemeter of the plurality of wavemeters has a first center wavelength (λ 1 ),
a second wavemeter of the plurality of wavemeters has a second center wavelength (λ 2 ),
a third wavemeter of the plurality of wavemeters has a third center wavelength (λ 3 ),
λ 3 =λ 1 +m/n *(λ 1 −λ 2 ),
m is an integer other than zero, and
n is equal to or smaller than a total number of wavemeters in the plurality of wavemeters.
18 . The photonic integrated circuit of claim 17 , wherein m is smaller than n.
19 . The photonic integrated circuit of claim 16 , wherein different wavemeters in the plurality of wavemeters have approximately equal free spectral ranges (FSRs).
20 . The photonic integrated circuit of claim 16 , wherein the plurality of wavemeters includes a phase calibration wavemeter.