Chi-Chia Huang

174-nm mode spacing in dual-wavelength semiconductor laser using nonidentical InGaAsP quantum wells

A very wide tuning range of dual-wavelength semiconductor lasers with properly designed nonidentical InGaAsP quantum wells is reported. As the external cavity of reflected-type grating telescope configuration is well aligned, the dual-wavelength operation can be achieved with a record wavelength separation as large as 174 nm (25 THz). The wide separation of two wavelengths is possible due to a proper modification of the external-cavity configuration and reduced gain competition of laser modes.

Anticompetition of laser modes

Anticompetition of laser modes is observed. In this behavior, the increase of intensity in one lasing mode could enhance the intensity of another mode, which is opposite to the usual competition behavior and so-called anticompetition. In our experiments using the semiconductor laser with very broadband gain medium, anticompetition exists when the laser modes have their wavelengths widely separated. Anticompetition can be observed for spectral separation of 138 nm and is even more prominent for spectral separation up to 167 nm. Theoretical analysis shows that anticompetition is due to the physics similar to optical pumping.

Investigation of laser-mode anticompetition in semiconductor lasers

Influential factors of laser-mode anticompetition are investigated in dual-wavelength semiconductor laser. Experiment shows that with increasing wavelength, separation, or decreasing initial power of the long-wavelength mode (LWM), the slope of the anticompetition curve and the maximum power increment of the LWM increase. Under fixed wavelength separation, anticompetition can exist only when the power of the short-wavelength mode (SWM) is below a certain level. In addition, the wavelength position has an effect on anticompetition. Different injection current also results in different behaviors of anticompetition. Anticompetition can only be observed with varying the power of the SWM.

Simultaneous generation of eight wavelengths with about 20-nm spacing from a single semiconductor laser

Simultaneous generation of eight wavelengths spanning from 1367.1 to 1526.9 nm with about 20-nm channel spacing is achieved using a single semiconductor laser. The full-width at half-maximum of each mode is smaller than 0.3 nm. The sidemode suppression ratio is larger than 28 dB and the ratio of the signal to the background noise is larger than 30 dB. With careful adjustment of the loss for each mode, the power difference among those modes can be less than 3 dB. The performance of the eight-wavelength laser system can be further improved with the reduced loss of the external cavity.

Mode competition in wide-range tunable dual-wavelength semiconductor laser using nonidentical InGaAsP quantum wells

Different mode competition has been observed in a wide-range tunable dual-wavelength semiconductor laser. When the wavelength separation is large enough, the competition behavior between the two modes is opposite to usual mode competition.

Semiconductor laser for all-optical switching between medium-wave band and long-wave band in optical fiber communication

Dual-wavelength semiconductor laser with wavelength separation as large as 203 nm is reported. With the short-wavelength mode located in 1345.4 nm and the long-wavelength mode in 1548.6 nm, the operation region of the laser system covers both the medium-wave band (1300 nm region) and long-wave band (1500 nm region) in optical communication. Random selection of oscillating wavelength position between 1345.4 nm and 1548.6 nm is also possible with fixed wavelength separation. This broadband laser system provides an opportunity for all-optical switching between the medium-wave band and long-wave band in optical communication.

Dual-wavelength semiconductor laser with 191-nm mode spacing

A very wide tuning range of dual-wavelength semiconductor lasers with properly designed nonidentical InGaAsP quantum wells is reported. By well aligning the external cavity, the dual-wavelength operation can be achieved with a record wavelength separation about 191 nm (27.4 THz) at 22.7°C. The wide separation of two wavelengths is possible due to a proper modification of the external-cavity configuration and reduced gain competition of laser modes.

A new type of gain nonlinearity leading to anti-competition of laser mode

Anti-competition of laser modes has been observed in dual-wavelength semiconductor laser with a broadband gain medium. This phenomenon is due to a new-type of gain nonlinearity in addition to the conventional gain saturation.