Page 453 - Tunable Lasers Handbook

8 Tunable External-Cavity Semiconductor Lasers 41 3

TABLE 7 Quantities and Measurement Techniques for ECLs

Parameter Instrument or method Resolutiodsensitivitg

Wavelength Optical spectrum analyzer Resolution -0.1 nm
Michelson interferometer wavelength meter resolution -5 ppm
Power Optical power meter resolution -0.01 dBm
Theshold cment Measurement of L-I curve under computer 0.Oj-mA resolution
control [ 1151 requires 2 to 3 sec per
wavelength
Sidemode ratio Scanning Fabry-Perot interferometer Sensitivity --I5 to -20 dB
Lighiwave signal analyzer [24] Sensitivity --60 dB
Linewidth Delayed-self-heterodyne method with minimum resolvable
Mach-Zender interferometer [ 1161 (Fig. 38) linewidth -% T~, where T~ is
the differential delay of ?he
interferometer

L 1 (77)
in*
Zo=-cc :[ +---In- (a)] +

One way to determine the internal parameters of the gain media is to sacrifice a
sampling of them by coating them with a partially reflective coating r1 on one
facet. The reflectance of the test film is measured from a witness sample. The
threshold current becomes

Assuming the laser diode still lases at Lo) the following relations for the internal
gain and loss parameters are obtained

and