What we call MKO (Mauna Kea Observatories) Y, J, H filters have been used for MCT
image sensor for a long time.
Vendors have produced the filters by hybrid, dielectric and silicon coatings to make
wide leak-blocking range, typically 0.4μm - 2.8μm.
However, transmission in passband was lower due to absorption of silicon coating.

RFQ on Y, J, H filter for InGaAs image sensor is nowadays increasing.
Sensitivity of InGaAs was 0.9μm - 1.7μm before, but the newest InGaAs has wider
sensitivity from optical region.

We succeeded in making Y, J, H filters that have blocking range from 0.4μm to 1.9μm
by all dielectric coatings without silicon coating and improving transmission in passband
significantly.