TY  - JOUR
A1  - Kurzke, Henning
A1  - Kiethe, Jan
A1  - Heuer, Axel
A1  - Jechow, Andreas
T1  - Frequency doubling of incoherent light from a superluminescent diode in a periodically poled lithium niobate waveguide crystal
JF  - Laser physics letters
N2  - The amplified spontaneous emission from a superluminescent diode was frequency doubled in a periodically poled lithium niobate waveguide crystal. The temporally incoherent radiation of such a superluminescent diode is characterized by a relatively broad spectral bandwidth and thermal-like photon statistics, as the measured degree of second order coherence, g((2))(0)= 1.9 +/- 0.1, indicates. Despite the non-optimized scenario in the spectral domain, we achieve six orders of magnitude higher conversion efficiency than previously reported with truly incoherent light. This is possible by using single spatial mode radiation and quasi phase matched material with a waveguide architecture. This work is a principle step towards efficient frequency conversion of temporally incoherent radiation in one spatial mode to access wavelengths where no radiation from superluminescent diodes is available, especially with tailored quasi phase matched crystals. The frequency doubled light might find application in imaging, metrology and quantum optics experiments.
KW  - nonlinear frequency conversion
KW  - periodically poled material
KW  - waveguides
KW  - incoherent radiation
Y1  - 2017
U6  - https://doi.org/10.1088/1612-202X/aa6889
SN  - 1612-2011
SN  - 1612-202X
VL  - 14
PB  - IOP Publ.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Kiethe, Jan
A1  - Heuer, Axel
A1  - Jechow, Andreas
T1  - Second-order coherence properties of amplified spontaneous emission from a high-power tapered superluminescent diode
JF  - Laser physics letters
N2  - We study the degree of second-order coherence of the emission of a high-power multi-quantum well superluminescent diode with a lateral tapered amplifier section with and without optical feedback. When operated in an external cavity, the degree of second-order coherence changed from the almost thermal case of g((2))(0)approximate to 1.9 towards the mostly coherent case of g((2)) (0) approximate to 1.2 when the injection current at the tapered section was increased. We found good agreement with semi-classical laser theory near and below threshold while above laser threshold a slightly higher g((2))(0) was observed. As a free running device, the superluminescent diode yielded more than 400 mW of optical output power with good spatial beam quality of M-slow(2) < 1.6. In this case, the degree of second-order coherence dropped only slightly from 1.9 at low powers to 1.6 at the maximum output power. To our knowledge, this is the first investigation of a high-power tapered superluminescent diode concerning the degree of second-order coherence. Such a device might be useful for real-world applications probing the second order coherence function, such as ghost imaging.
KW  - photon statistics
KW  - incoherent light
KW  - superluminescent diodes
Y1  - 2017
U6  - https://doi.org/10.1088/1612-202X/aa772c
SN  - 1612-2011
SN  - 1612-202X
VL  - 14
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  -