Wavelength stabilized light source
An apparatus for producing wavelength stabilized electromagnetic radiation is provided, the apparatus comprising a broadband semiconductor radiation source configured to produce broadband electromagnetic radiation having a mean wavelength λ m , and a bandpass radiation filter, an input of said bandpass radiation filter being in optical connection to an output of said radiation source, and a common temperature stabilizer being in thermal contact with both, the radiation source and the radiation filter. In a preferred embodiment, the radiation source—which is, for example, a superluminescent light emitting diode—and the bandpass radiation filter are provided on a common mount which is in contact with a thermoelectric cooler acting, together with temperature sensing means and control means, as temperature stabilizer.
1. An apparatus for producing wavelength stabilized electromagnetic radiation, the apparatus comprising a broadband semiconductor radiation source configured to provide broadband electromagnetic radiation having a mean wavelength λ m , and a bandpass radiation filter, an input of said bandpass radiation filter being in optical connection to an output of said radiation source, and a common temperature stabilizer being in thermal contact with both, the radiation source and the radiation filter.
2. The apparatus according to claim 1 , the temperature stabilizer comprising a thermoelectric cooler, a temperature sensor being in thermal contact with the radiation source and the radiation filter and a controller an input of which is operatively connected to the temperature sensor and an output of which is operatively connected to the thermoelectric cooler.
3. The apparatus according to claim 2 , wherein the controller comprises an analog electronic control circuit and is absent any analog-to-digital conversion stage.
4. The apparatus according to claim 2 , wherein the controller comprises a digital signal processing unit.
5. The apparatus according to claim 1 further comprising a mount, the radiation source and the radiation filter being mechanically connected to said mount, the mount being in thermal contact with the temperature stabilizer.
6. The apparatus according to claim 5 , the temperature stabilizer comprising a thermoelectric cooler, the mount being mounted on the thermoelectric cooler.
7. The apparatus according to claim 1 , the broadband electromagnetic radiation comprising a broadband electromagnetic radiation bandwidth, the bandpass radiation filter comprising a filter bandwidth, the filter bandwidth being smaller than the radiation bandwidth.
8. The apparatus according to claim 7 , the broadband electromagnetic radiation having a mean wavelength λ m , wherein within a wavelength span Δλ which includes the mean wavelength and with Δλ/λ m >0.05 the spectral power does not vary by more than 0.8 dB.
9. The apparatus according to claim 1 , wherein the mean wavelength is in the near infrared region.
10. The apparatus according to claim 1 , wherein the semiconductor radiation source comprises a non-lasing superluminescent light emitting diode.
11. The apparatus according to claim 10 , wherein the semiconductor radiation source further comprises a second non-lasing superluminescent light emitting diode, the second non-lasing superluminescent light emitting diode having an emission characteristics different from the emission characteristics of the first non-lasing superluminescent light emitting diode.
12. A system for generating electromagnetic radiation comprising a package of at least one superluminescent light emitting diode operable to emit primary electromagnetic radiation with a first bandwidth and a band pass filter capable of filtering the primary radiation to yield secondary radiation with a second bandwidth, which is smaller than the first bandwidth, an input of the band pass filter being optically coupled to an output of the at least one superluminescent light emitting diode, the package being thermally coupled to a thermoelectric cooler, the system further comprising a temperature sensor being in thermal contact with the package and a controller operable to control the thermoelectric cooler based on signals input from the temperature sensor.
13. The system according to claim 12 , the primary electromagnetic radiation having a mean wavelength λ m , wherein within a wavelength span Δλ which includes the mean wavelength and with Δλ/λ m >0.05 the spectral power does not vary by more than 0.8 dB.
14. The system according to claim 12 , comprising a fiber optically coupled to an output of said band pass filter, so that radiation output by the filter is couplable into the fiber, the fiber being at least one of a single mode fiber and of a polarization maintaining fiber.
15. The system according to claim 12 further comprising an optical arrangement including a fiber coil into which radiation output by the filter is couplable, the optical arrangement being capable of detecting a change of orientation of the fiber coil with respect to one spatial direction.