Page 441 - Tunable Lasers Handbook

8 Tunable External-Cavity Semiconductor lasers 401

FIGURE 29 Littrowgrating extended-cavity laser with a GRIN rod lens collimator and intra-
cavity silicon prism beam expanders. (Reproduced with permission from Zorabedizn [61]. )

AR coating AR coating

"U
6.5 mm tampered
Grating
FL amplifier
lens chip
FlGURE 3 0 Littrowgrating extended-cavity laser with tapered-stripe gain chip. (Reproduced
lvith permission from IvIehuys et a/. [13] and IEE Publishing.)

ANTIREFLECTION
COATED
DIODE LASER

ANTIREFLECTION
COATED LENSES
FlGU RE 2; 1 Grating-tuned double-ended extended cavity laser. (Reproduced with permission
from Fleming and Mooradian [38]. 0 1981 1EEE.j

isolator to force traveling-wave operation (Fig. 32). They estimated that the
effective reflectance of each facet due to the 7" stripe angle was -1 x 10-4. Total
tuning range was 45 nm, with up to 23-mW cur free-space output power. A
delayed-self-homodyne measurement was used to determine the longitudinal
mode characteristics. Over a 35-nm range, quasi-single-mode oscillation was
obtained, but the sidemode suppression was less than 20 dB, and the linewidth
was -500 kHz. A 1200 groove/mm grating increased the sidemade suppression