T. Mukaihara

Low loss 1×93 wavelength selective switch using PLC-based spot size converter

A massive port count WSS using planar lightwave circuit as optical input/output ports is proposed. We demonstrate a 1×93 LCOS-based WSS with less than 9.0 dB insertion loss and typically 37.0 GHz 0.5 dB passband width.

Future narrow linewidth lasers

We describe the challenges and solutions for future narrow linewidth lasers with small footprint. We fabricated DR laser array based narrower linewiedth TLS. We introduce ITXA of a co-packaged DFB array based TLS and InP-based modulator.

1550 nm AlGaInAs/InP widely tunable BH laser based on arrayed DFB

We have fabricated high performance 1550nm both solitary lasers and the 12-channel arrayed DFB/SOA integrated widely tunable lasers with buried-heterostructure configuration in the AlGaInAs/InP system. An output power of 100mW was obtained for tunable lasers at 20°C.

High-efficiency heater-loaded wavelength selectable laser

We have fabricated wavelength selectable lasers loaded with high-efficiency TiPt heater. Wavelength tuning by use of comb-shaped heater structure on DFB lasers array, temperature arise of SOA was suppressed, resulting in drastic improvement for the variation of optical output power at high temperature. Tuning range of 9.8 nm for wavelength selectable laser integrating four DFB lasers was realized with heater power consumption of as low as 0.36 W.

High output power widely tunable laser module

We have developed highly reliable widely tunable module, whose performances were comparable with fixed-wavelength DFB laser module. To realize wide tunability, 12 l/4-shifted DFB laser array, S-bend waveguides, MMI coupler and an SOA were integrated on a chip. We could achieve 37nm tunability by controlling each chip temperature in the range of 5 to 45°C. High output fiber coupled power of 30mW and very uniform L-I curves out of 12 DFB lasers were achieved even at 50°C. Good quality of lasing spectrum was obtained. Side mode suppression ratio (SMSR) > 45dB. The well-suppressed reflection at chip front facet contributed to the lower noise characteristics, such as RIN < -140dB/Hz and linewidth < 4MHz. The shift of locked frequency was less than 0.4GHz as the case temperature varied from -5 to 75°C. Very small frequency shift was realized by controlling the temperature of locker part, independently. By optimizing TEC design, we could achieve low TEC power consumption less than 4W under Tcase=75°C and the end of life condition of SOA current. The new function by incorporating SOA was VOA. By changing the operating SOA current, we could vary output power from 1mW to 20mW, maintaining SMSR > 40dB, RIN < -135dB/Hz, linewidth < 4MHz. We also performed optical blocking > 40dB, when SOA current was turned off. We examined modules reliability under high temperature storage of 85°C. The change of output power was < ± 10%, and the shift of locked frequency was < ± 5pm after 2000 hours.

1.3 /spl mu/m GaInAsP lasers integrated with monitoring photodiodes through highly reflective semiconductor/air Bragg reflector (SABAR)

We have demonstrated an integration with a laser and a monitoring photodiode through a highly reflective semiconductor/air Bragg reflector (SABAR), for the first time. Experimentally obtained SABAR reflectivity is as high as 80%. Threshold characteristics of ridge waveguide lasers and photocurrent behavior of monitor photodiodes are evaluated.

High performance 1.3 /spl mu/m InAsP SL-QW ACIS (Al-oxide confined inner stripe) lasers

A low threshold of 2 mA, a high quantum efficiency of 67% and a stable single transverse mode operations have been obtained in newly developed 1.3 μm Al-oxide confined inner stripe (ACIS) lasers with modulation-doped quantum wells.

Narrow linewidth tunable lasers for digital coherent system

We describe μ-ITLA characteristics with DFB/DR laser array based narrow linewidth tunable laser. We also introduce ITXA of a co-packaged DFB array based laser and InP-based modulator for metro digital coherent application.

Widely tunable lasers based on mode-hop-free semiconductor laser array

Integration of mode-hop-free tunable laser array and a semiconductor optical amplifier is most reliable approach to realize widely tunable lasers. We have developed two types of tunable lasers, one is a thermally tunable DFB laser array for DWDM tunable transponders, which has shown high power and wide tunability covering Cband or L-band, housing in compact butterfly packages with robust wavelength locker. Another is a short-cavity DBR laser array for optical burst switching, whose lasing frequency can be monotonously tuned and locked on the ITU grid within 5 microseconds. Both lasers have demonstrated superior performances in system experiments.

High PMF coupled output power, 37 nm tunable laser module using matrix DFB laser

We have fabricated the thermally controlled, widely tunable laser module using matrix DFB laser. To realize high output power and wide tunability simultaneously, 12 DFB lasers were integrated in the form of 2 /spl times/ 6 matrix with low loss 1 /spl times/ 6 multi mode interferometer coupler and semiconductor optical amplifier. Optimizing lasing wavelength of the DFB lasers, stable single mode operations with side mode suppression ratio of over 40 dB were obtained. The module has shown excellent characteristics, such as high polarization maintaining optical fiber coupled power over 30 mW and wide tunability over 37 nm.